Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activation of the cAMP/PKA signaling pathway.

BACKGROUND AND AIMS: Vascular calcification (VC) is regarded as an independent risk factor for cardiovascular events in type 2 diabetic patients. Glucose transporter 1 (GLUT1) involves VC. Intermedin/Adrenomedullin-2 (IMD/ADM2) is a cardiovascular protective peptide that can inhibit multiple disease-associated VC. However, the role and mechanism of IMD in diabetic VC remain unclear. Here, we investigated whether IMD inhibits diabetic VC by inhibiting GLUT1. METHODS AND RESULTS: It was found that plasma IMD concentration was significantly decreased in type 2 diabetic patients and in fructose-induced diabetic rats compared with that in controls. Plasma IMD content was inversely correlated with fasting blood glucose level and VC severity. IMD alleviated VC in fructose-induced diabetic rats. Deficiency of Adm2 aggravated and Adm2 overexpression attenuated VC in high-fat diet-induced diabetic mice. In vitro, IMD mitigated high glucose-induced calcification of vascular smooth muscle cells (VSMCs). Mechanistically, IMD reduced advanced glycation end products (AGEs) content and the level of receptor for AGEs (RAGE). IMD decreased glucose transporter 1 (GLUT1) levels. The inhibitory effect of IMD on RAGE protein level was blocked by GLUT1 knockdown. GLUT1 knockdown abolished the effect of IMD on alleviating VSMC calcification. IMD receptor antagonist IMD17-47 and cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) inhibitor H89 abolished the inhibitory effects of IMD on GLUT1 and VSMC calcification. CONCLUSIONS: These findings revealed that IMD exerted its anti-calcification effect by inhibiting GLUT1, providing a novel therapeutic target for diabetic VC.

Gut microbiome alterations in colitis rats after moxibustion at bilateral Tianshu acupoints.

BACKGROUND: The pathogenesis of ulcerative colitis (UC) is closely related to the gut microbiota. Moxibustion has been used to improve the inflammation and gastrointestinal dysfunctions in gastrointestinal disorders such as UC. In this study, we investigated whether moxibustion could improve the gut microbial dysbiosis induced by dextran sulphate sodium. METHODS: Twenty-five male rats were randomly assigned into five groups. The UC rat model was established by administering DSS solution. The rats in the moxibustion and normal rats with moxibustion groups were treated with moxibustion at Tianshu (bilateral, ST25) points, and the mesalazine group rats were treated with mesalazine once daily for 7 consecutive days. Disease activity index (DAI) and haematoxylin and eosin staining were used to evaluate the effect of moxibustion. Gut microbiota profiling was conducted by metagenomic high throughput sequencing technology. The gut microbiota composition, diversity and function were analyzed and compared using metagenomics methodologies. RESULTS: The DAI scores and histopathology scores in the moxibustion and mesalazine groups were significantly decreased compared with the UC group (P < 0.01). Moxibustion treatment increased abundance levels of Bacteroidetes, Actinobacteria, Ascomycota, Synergistetes and decreased abundance of Firmicutes, Proteobacteria. At the genus level, the abundance of Bacteroides, Bacteroides_bacterium_M7, Prevotella, Bacteroidales_bacterium_H2, were increased and Bacteroides_bacterium_H3, Parabacteroides, Porphyromonas, Alistipes, Parasutterella were decreased in the UC group in comparsion with those in the NG group. Moxibustion increased the abundance of Bacteroides and Bacteroides_bacterium_H3 and decreased Bacteroides_bacterium_M7, Prevotella, Bacteroidales_bacterium_H2. In UC group, the specie Bacteroides_massiliensis was negatively (P < 0.05) correlated with IL-23, Bacteroides_eggerthii_CAG109 and Bacteroides_eggerthii were negatively (P < 0.05) correlated with TGF-ß. And the species Prevotella_sp_CAG1031 and Bacteroides_bacterium_H2 were significant positively (P < 0.05) correlated with IL-23. In addition, compare with the normal group, genes involved in certain metabolic pathways, such as energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, were under-represented in the UC group, and these changes in the metabolic pathways could be reversed by moxibustion treatment and mesalazine treatment. CONCLUSIONS: Our findings suggest that moxibustion treatment may protect the host from mucosal inflammation by modulating the intestinal microbiota community.

Intermedin1-53 Inhibits NLRP3 Inflammasome Activation by Targeting IRE1α in Cardiac Fibrosis.

Intermedin (IMD), a paracrine/autocrine peptide, protects against cardiac fibrosis. However, the underlying mechanism remains poorly understood. Previous study reports that activation of nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome contributes to cardiac fibrosis. In this study, we aimed to investigate whether IMD mitigated cardiac fibrosis by inhibiting NLRP3. Cardiac fibrosis was induced by angiotensin II (Ang II) infusion for 2 weeks in rats. Western blot, real-time PCR, histological staining, immunofluorescence assay, RNA sequencing, echocardiography, and hemodynamics were used to detect the role and the mechanism of IMD in cardiac fibrosis. Ang II infusion resulted in rat cardiac fibrosis, shown as over-deposition of myocardial interstitial collagen and cardiac dysfunction. Importantly, NLRP3 activation and endoplasmic reticulum stress (ERS) were found in Ang II-treated rat myocardium. Ang II infusion decreased the expression of IMD and increased the expression of the receptor system of IMD in the fibrotic rat myocardium. IMD treatment attenuated the cardiac fibrosis and improved cardiac function. In addition, IMD inhibited the upregulation of NLRP3 markers and ERS markers induced by Ang II. In vitro, IMD knockdown by small interfering RNA significantly promoted the Ang II-induced cardiac fibroblast and NLRP3 activation. Moreover, silencing of inositol requiring enzyme 1 α (IRE1α) blocked the effects of IMD inhibiting fibroblast and NLRP3 activation. Pre-incubation with PKA pathway inhibitor H89 blocked the effects of IMD on the anti-ERS, anti-NLRP3, and anti-fibrotic response. In conclusion, IMD alleviated cardiac fibrosis by inhibiting NLRP3 inflammasome activation through suppressing IRE1α via the cAMP/PKA pathway.

Intermedin1-53 attenuates atherosclerotic plaque vulnerability by inhibiting CHOP-mediated apoptosis and inflammasome in macrophages.

Atherosclerotic plaque vulnerability and rupture increase the risk of acute coronary syndromes. Advanced lesion macrophage apoptosis plays important role in the rupture of atherosclerotic plaque, and endoplasmic reticulum stress (ERS) has been proved to be a key mechanism of macrophage apoptosis. Intermedin (IMD) is a regulator of ERS. Here, we investigated whether IMD enhances atherosclerotic plaque stability by inhibiting ERS-CHOP-mediated apoptosis and subsequent inflammasome in macrophages. We studied the effects of IMD on features of plaque vulnerability in hyperlipemia apolipoprotein E-deficient (ApoE-/-) mice. Six-week IMD1-53 infusion significantly reduced atherosclerotic lesion size. Of note, IMD1-53 lowered lesion macrophage content and necrotic core size and increased fibrous cap thickness and vascular smooth muscle cells (VSMCs) content thus reducing overall plaque vulnerability. Immunohistochemical analysis indicated that IMD1-53 administration prevented ERS activation in aortic lesions of ApoE-/- mice, which was further confirmed in oxidized low-density lipoproteins (ox-LDL) induced macrophages. Similar to IMD, taurine (Tau), a non-selective ERS inhibitor significantly reduced atherosclerotic lesion size and plaque vulnerability. Moreover, C/EBP-homologous protein (CHOP), a pro-apoptosis transcription factor involved in ERS, was significantly increased in advanced lesion macrophages, and deficiency of CHOP stabilized atherosclerotic plaques in AopE-/- mice. IMD1-53 decreased CHOP level and apoptosis in vivo and in macrophages treated with ox-LDL. In addition, IMD1-53 infusion ameliorated NLRP3 inflammasome and subsequent proinflammatory cytokines in vivo and in vitro. IMD may attenuate the progression of atherosclerotic lesions and plaque vulnerability by inhibiting ERS-CHOP-mediated macrophage apoptosis, and subsequent NLRP3 triggered inflammation. The inhibitory effect of IMD on ERS-induced macrophages apoptosis was probably mediated by blocking CHOP activation.

Inhibition of Notch1-mediated inflammation by intermedin protects against abdominal aortic aneurysm via PI3K/Akt signaling pathway.

The Notch1-mediated inflammatory response participates in the development of abdominal aortic aneurysm (AAA). The vascular endogenous bioactive peptide intermedin (IMD) plays an important role in maintaining vascular homeostasis. However, whether IMD inhibits AAA by inhibiting Notch1-mediated inflammation is unclear. In this study, we found Notch intracellular domain (NICD) and hes1 expression were higher in AAA patients' aortas than in healthy controls. In angiotensin II (AngII)-induced AAA mouse model, IMD treatment significantly reduced AAA incidence and maximal aortic diameter. IMD inhibited AngII-enlarged aortas and -degraded elastic lamina, reduced NICD, hes1 and inflammatory factors expression, decreased infiltration of CD68 positive macrophages and the NOD-like receptor family pyrin domain containing 3 protein level. IMD inhibited lipopolysaccharide-induced macrophage migration in vitro and regulated macrophage polarization. Moreover, IMD overexpression significantly reduced CaCl2-induced AAA incidence and down-regulated NICD and hes1 expression. However, IMD deficiency showed opposite results. Mechanically, IMD treatment significantly decreased cleavage enzyme-a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) level. Pre-incubation with IMD17-47 (IMD receptors blocking peptide) and the phosphatidylinositol 3-kinase/protein kinase b (PI3K/Akt) inhibitor LY294002 reversed ADAM10 level. In conclusion, exogenous and endogenous IMD could inhibit the development of AAA by inhibiting Notch1 signaling-mediated inflammation via reducing ADAM10 through IMD receptor and PI3K/Akt pathway.

STAT3 Promotes Schistosome-Induced Liver Injury by Inflammation, Oxidative Stress, Proliferation, and Apoptosis Signal Pathway.

Schistosomiasis is a parasitic helminth disease that can cause organ lesions leading to health damage. During a schistosome infection, schistosome eggs can flow into the liver along the portal vein. Numerous inflammatory cells gather around the eggs, causing granulomas and fibrosis in the liver. In this process, many molecules are involved in the initiation and regulation of the fibrous scar formation. However, the precise molecular mechanisms responsible for the progression of granuloma formation and fibrosis initiation caused by schistosome infection have not been extensively studied. In this study, C57BL/6 wild-type mice and Stat3flox/flox Alb-Cre mice were infected with cercariae of Schistosoma japonicum Liver injury, effector molecule levels, and RNA transcriptome resequencing of liver tissue were detected at 4, 5, and 6 weeks postinfection. We investigated the role of STAT3 (signal transducer and activator of transcription 3) in Schistosoma-induced liver injury in mice. After 6 weeks postinfection, there was obvious liver fibrosis. A sustained pathological process (inflammation, oxidative stress, proliferation, and apoptosis) occurred in S. japonicum-induced liver fibrosis initiation. Meanwhile, we observed activation of the STAT3 pathway in hepatic injury during S. japonicum infection by RNA transcriptome resequencing. Liver deficiency of phospho-STAT3 alleviated infection-induced liver dysfunction, hepatic granuloma formation, and fibrosis initiation. It also promoted STAT3-dependent apoptosis and reduced liver inflammation, oxidative stress, and proliferation. Our results suggest that STAT3 signal pathway and its mediating inflammation, oxidative stress, proliferation, and apoptosis are involved in S. japonicum-induced liver injury and may be a new potential guideline for the treatment of schistosomiasis.

Intermedin alleviates pathological cardiac remodeling by upregulating klotho.

Cardiac remodeling is accompanied by cardiac hypertrophy, fibrosis, dysfunction, and eventually leading to heart failure. Intermedin (IMD), as a paracrine/autocrine peptide, has a protective effect in cardiovascular diseases. In this study, we elucidated the role and the underlying mechanism of IMD in pathological remodeling. Pathological remodeling mouse models were induced by abdominal aorta constriction for 4 weeks or angiotensin II (Ang II) infusion for 2 weeks in wildtype, IMD-overexpression, IMD-knockout and klotho-knockdown mice. Western blot, real-time PCR, histological staining, echocardiography and hemodynamics were used to detect the role of IMD in cardiac remodeling. Cardiac hypertrophy, fibrosis and dysfunction were significantly aggravated in IMD-knockout mice versus wildtype mice, and the expression of klotho was downregulated. Conversely, cardiac remodeling was alleviated in IMD-overexpression mice, and the expression of klotho was upregulated. Hypertension induced by Ang II infusion rather than abdominal aorta constriction was mitigated by IMD. However, the cardioprotective effect of IMD was blocked in klotho-knockdown mice. Similar results were found in cultured neonatal rat cardiomyocytes, which was pretreated with IMD before Ang II stimulation. Mechanistically, IMD inhibited the phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and the activity of calcineurin to protect against cardiac hypertrophy through upregulating klotho in vivo and in vitro. Furthermore, peroxisome proliferator-activated receptor γ (PPARγ) might mediate IMD upregulating klotho. In conclusion, pathological remodeling may be alleviated by endogenous IMD, which inhibits the expression of calcineurin and p-CaMKII by upregulating klotho via the PPARγ pathway. It suggested that IMD might be a therapeutic target for heart disease.

Intermedin1-53 attenuates aging-associated vascular calcification in rats by upregulating sirtuin 1.

Vascular calcification is a common phenomenon in older adults. Intermedin (IMD) is a cardiovascular bioactive peptide inhibiting vascular calcification. In this study, we aimed to investigate whether IMD1-53 attenuates aging-associated vascular calcification. Vascular calcification was induced by vitamin D3 plus nicotine (VDN) in young and old rats. The calcification in aortas was more severe in old rats treated with VDN than young control rats, and IMD expression was lower. Exogenous administration of IMD1-53 significantly inhibited the calcium deposition in aortas and the osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) in VDN-treated old rats. Moreover, levels of aging-related p16, p21 and ß-galactosidase were all greatly decreased by IMD1-53. These results were further confirmed in rat and human VSMCs in vitro. In addition, IMD-deficient mouse VSMCs showed senescence features coinciding with osteogenic transition as compared with wild-type mouse VSMCs. Mechanistically, IMD1-53 significantly increased the expression of the anti-aging factor sirtuin 1 (sirt1); the inhibitory effects of IMD1-53 on calcification and senescence were blocked by sirt1 knockdown. Furthermore, preincubation with inhibitors of PI3K, AMPK or PKA efficiently blunted the upregulatory effect of IMD1-53 on sirt1. Consequently, IMD1-53 could attenuate aging-associated vascular calcification by upregulating sirt1 via activating PI3K/Akt, AMPK and cAMP/PKA signaling.

Intermedin1-53 Ameliorates Homocysteine-Promoted Atherosclerotic Calcification by Inhibiting Endoplasmic Reticulum Stress.

AIM: Vascular calcification (VC) is thought to be an independent predictor of cardiovascular morbidity and mortality. Intermedin1-53 (IMD) is a cardiovascular protective peptide and can inhibit vascular medial calcification in rats. In this study, we investigated the effect of IMD on atherosclerotic calcification induced by a high-fat diet plus homocysteine (Hcy) and the potential mechanisms. METHODS: ApoE-/- mice were fed a high-fat diet with Hcy in drinking water to induce atherosclerotic calcification. RESULTS: As compared to the high-fat diet alone, Hcy treatment significantly increased atherosclerotic lesion areas and the number of calcified nodules in aortic roots and was reduced by IMD infusion or 4-phenylbutyric acid (PBA) treatment. In vitro, as compared to calcifying medium alone, Hcy treatment further increased alkaline phosphatase activity, calcium content, and calcium nodule number in human aorta vascular smooth muscle cells (HA-VSMCs), all blocked by IMD or PBA pretreatment. Mechanistically, IMD or PBA significantly alleviated endoplasmic reticulum stress (ERS) activation compared with Hcy treatment. In parallel, IMD or PBA attenuated the messenger RNA levels of osteogenic markers and inflammatory cytokines in aortas and their protein levels in lesions of aortic roots. In vitro, Hcy treatment significantly increased the protein levels of osteoblast-like cell markers in primary rat VSMCs and inflammation markers in mouse peritoneal macrophages, all decreased with IMD or PBA pretreatment. Intermedin1-53 pretreatment also markedly reduced the protein levels of ERS markers in rat VSMCs and mouse peritoneal macrophages. CONCLUSIONS: Intermedin1-53 protects against Hcy-promoted atherosclerotic calcification in ApoE-/- mice by inhibiting ERS.

Taurine Alleviates Schistosoma-Induced Liver Injury by Inhibiting the TXNIP/NLRP3 Inflammasome Signal Pathway and Pyroptosis.

Schistosomiasis is a parasitic helminth disease that can cause severe inflammatory pathology, leading to organ damage, in humans. During a schistosomal infection, the eggs are trapped in the host liver, and products derived from eggs induce a polarized Th2 cell response, resulting in granuloma formation and eventually fibrosis. Previous studies indicated that the nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is involved in schistosomiasis-associated liver fibrosis and that taurine could ameliorate hepatic granulomas and fibrosis caused by Schistosoma japonicum infection. Nevertheless, the precise role and molecular mechanism of the NLRP3 inflammasome and the protective effects of taurine in S. japonicum infection have not been extensively studied. In this study, we investigated the role of the NLRP3 inflammasome and the hepatoprotective mechanism of taurine in schistosoma-induced liver injury in mice. NLRP3 deficiency ameliorated S. japonicum-infection-induced hepatosplenomegaly, liver dysfunction, and hepatic granulomas and fibrosis; it also reduced NLRP3-dependent liver pyroptosis. Furthermore, taurine suppressed hepatic thioredoxin-interacting protein (TXNIP)/NLRP3 inflammasome activation in mice with S. japonicum infections, thereby inhibiting the activation of downstream inflammatory mediators such as interleukin-1ß and subsequent pyroptosis. Our results suggest that the TXNIP/NLRP3 inflammasome pathway and mediating pyroptosis are involved in S. japonicum-induced liver injury and may be a potential therapeutic target for schistosomiasis treatment. In addition, taurine may be useful to alleviate or to prevent the occurrence of schistosomiasis-associated liver fibrosis.

Endogenous intermedin protects against intimal hyperplasia by inhibiting endoplasmic reticulum stress.

Extensive proliferation of vascular smooth muscle cell (VSMC) contributes to intimal hyperplasia following vascular injury, in which endoplasmic reticulum stress (ERS) plays a critical role. Intermedin (IMD) is a vascular paracrine/autocrine peptide exerting numerous beneficial effects in cardiovascular diseases. IMD overexpression could alleviate intimal hyperplasia. Here, we investigated whether endogenous IMD protects against intimal hyperplasia by inhibiting endoplasmic reticulum stress. The mouse left common carotid-artery ligation-injury model was established to induce intimal hyperplasia using IMD-/-mice and C57BL/6 J wild-type (WT) mice. Platelet-derived growth factor-BB (PDGF-BB) was used to stimulate the proliferation of VSMC. IMD-/- mice displayed exacerbated intimal hyperplasia induced by complete ligation of the left carotid artery at 14 d and 28 d compared to WT mice. However, IMD-deficiency had no effect on blood pressure, plasma triglyceride, and fasting blood glucose levels in mice. Furthermore, VSMCs derived from IMD-/- mice showed increased cell proliferation and dramatically elevated levels of glucose regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), ATF6 mRNA under PDGF-BB treatment compared to WT mice-derived VSMCs. In addition, exogenous administration of IMD significantly attenuated PDGF-BB-induced cell proliferation and GRP78, phosphorylase-inositol requiring enzyme 1α, ATF4, and ATF6 protein levels. Thus, endogenous IMD may counteract ERS to exert protective role in response to vascular injury and IMD is expected to be a therapeutic target for the prevention and treatment of restenosis.

Moxibustion treatment modulates the gut microbiota and immune function in a dextran sulphate sodium-induced colitis rat model.

AIM: To investigate the effect and mechanism of moxibustion in rats with ulcerative colitis. METHODS: A rat colitis model was established by administering 4% dextran sulphate sodium solution. Seventy male rats were randomly divided into seven groups: Healthy controls (HC), ulcerative colitis model group (UC), UC with 7 d of moxibustion (UC-7), UC with 14 d of moxibustion (UC-14), UC with mesalazine gavage (UC-W), HC with 7 d of moxibustion (HC-7), HC with 14 d of moxibustion (HC-14). Moxibustion was applied to the bilateral Tianshu (ST25). Gut microbiome profiling was conducted by 16S rRNA amplicon sequencing, and PCR and ELISA determined the expression of inflammatory cytokines in colon mucosa and serum, respectively. RESULTS: Moxibustion treatment restored the colonic mucosa and decreased submucosal inflammatory cell infiltration in colitis rats. Rats treated with moxibustion and mesalazine had significantly lower levels of the dominant phyla Proteobacteria and the genera Saccharibacteria, Sphingomonas and Barnesiella than colitis rats, and they could restore the microbiome to levels similar to those observed in healthy rats. UC rats had reduced alpha diversity, which could be alleviated by moxibustion therapy, and UC-7 had a higher alpha diversity than UC-14. This finding suggests that short-term (7 d) but no longer term (14 d) moxibustion treatment may significantly affect the gut microbiome. The potential bacterial functions affected by moxibustion may be ascorbate and aldarate metabolism, and amino acid metabolism. Compared with HC group, the levels of the cytokines interleukin-12 (IL-12) (P < 0.05) and IL-6, IL-17, IL-23, interferon-γ, lipopolysaccharide, IgA, tumour necrosis factor-α and its receptors 1 (TNFR1) and TNFR2 (P < 0.01) were all increased, whereas anti-inflammatory cytokine IL-2 and IL-10 (P < 0.01) and transforming growth factor-ß (P < 0.05) were decreased in UC rats. These changes were reversed by moxibustion. CONCLUSION: Our findings suggest that moxibustion exerts its therapeutic effect by repairing mucosal tissue damage and modulating the gut microbiome and intestinal mucosal immunity.

Intermedin reduces neointima formation by regulating vascular smooth muscle cell phenotype via cAMP/PKA pathway.

BACKGROUND AND AIMS: Vascular smooth muscle cell (VSMC) dedifferentiation contributes to neointima formation, which results in various vascular disorders. Intermedin (IMD), a cardiovascular paracrine/autocrine polypeptide, is involved in maintaining circulatory homeostasis. However, whether IMD protects against neointima formation remains largely unknown. The purpose of this study is to investigate the role of IMD in neointima formation and the possible mechanism. METHODS: IMD1-53 (100ng/kg/h) or saline water was used on rat carotid-artery balloon-injury model. The mouse left common carotid-artery ligation-injury model was established using IMD-transgenic and C57BL/6J mice. Immunohistochemistry and immunofluorescence staining was used to detect the protein expression in rat carotid arteries. Radioimmunoassay was used to determine the serum IMD level. The hematoxylin andeosin staining was used for carotid arteries morphological testing. In vitro, for rat primary cultured VSMC phenotype transition, proliferation and migration assays, platelet-derived growth factor-BB (PDGF-BB) reagent and IMD1-53 peptide were added to the culture media at the final concentration of 20 ng/mL and 10-7mol/L respectively. Quantification of VSMC proliferation involved MTT and BrdU assay and migration was detected by wound-healing assay. Western blot and realtime PCR were used to detect the protein and mRNA levels of tissues or cells. RESULTS: With the rat carotid-artery balloon-injury model, IMD was significantly downregulated in injured arteries and plasma. Exogenous IMD1-53 greatly inhibited neointima formation and prevented VSMC from switching to a synthetic phenotype. With the left common carotid-artery ligation-injury model, IMD-transgenic mice showed less neointima formation than C57BL/6J mice. PDGF-BB reduced IMD mRNA expression in rat primary cultured VSMCs but increased that of its receptors, calcitonin receptor-like receptor or receptor activity-modifying proteins. Furthermore, PDGF-BB promoted VSMC proliferation and migration and transformed VSMCs to the synthetic phenotype, which was reversed with IMD1-53 treatment. Mechanistically, IMD1-53 maintained the contractile VSMC phenotype via the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) pathway. CONCLUSIONS: IMD attenuated neointima formation both in the rat model of carotid-artery balloon injury and mouse model of common carotid-artery ligation injury. IMD protection may be mediated by maintaining a VSMC contractile phenotype via the cAMP/PKA pathway.