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Inhibition of allograft inflammatory factor-1 expression reduces development of neointimal hyperplasia and p38 kinase activity.

ABSTRACT: Allograft inflammatory factor-1 (AIF-1) is a calcium-binding, scaffold-signalling protein expressed in vascular smooth muscle cells (VSMCs) in response to injury. The effects of AIF-1 attenuation on development of intimal hyperplasia are unknown, and the molecular mechanisms of these effects remain uncharacterized. The goals of the present study were to determine whether AIF-1 knockdown reduced VSMC proliferation, migration, and intimal hyperplasia, and determine AIF-1 effects on signal transduction in VSMCs.Balloon angioplasty-injured rat carotid arteries transduced with adenovirus to overexpress AIF-1 (AdAIF-1) significantly increased, and adenovirus to knock down AIF-1 (AdsiRNA) expression significantly decreased neointimal formation compared with green fluorescent protein (AdGFP) and Adscrambled controls (P < 0.05 and P < 0.01, n = 6). Primary rat VSMCs transduced with AdAIF-1 displayed a significant increase in proliferation, and AdsiRNA-transduced VSMCs proliferated significantly more slowly than controls (P < 0.05). VSMCs transduced with AdAIF-1 show increased migration when compared with control VSMCs (P < 0.01). Rat VSMCs transduced with AdAIF-1 showed constitutive and prolonged activation of the mitogen-activated protein kinase p38, whereas AdsiRNA-treated VSMCs showed decreased p38 activation compared with AdGFP (P < 0.05). Immunohistochemical analysis of AdAIF-1-transduced carotid arteries showed increased staining with a phospho-specific p38 antibody compared with AdGFP-transduced arteries. A specific p38 inhibitor abrogated AIF-1-induced VSMC proliferation, but not AIF-1-induced migration.Taken together, AIF-1 expression plays a key role in the development of neointimal hyperplasia. AIF-1 expression enhances the activation of p38 MAP kinase. AIF-1-enhanced proliferation is p38 kinase dependent, but AIF-1-enhanced VSMC migration is p38 independent.

SUBMITTER: Sommerville LJ

PROVIDER: S-EPMC2721640 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Inhibition of allograft inflammatory factor-1 expression reduces development of neointimal hyperplasia and p38 kinase activity.

Sommerville Laura J LJ Xing Chen C Kelemen Sheri E SE Eguchi Satoru S Autieri Michael V MV

Cardiovascular research 20080908 1

<h4>Aims</h4>Allograft inflammatory factor-1 (AIF-1) is a calcium-binding, scaffold-signalling protein expressed in vascular smooth muscle cells (VSMCs) in response to injury. The effects of AIF-1 attenuation on development of intimal hyperplasia are unknown, and the molecular mechanisms of these effects remain uncharacterized. The goals of the present study were to determine whether AIF-1 knockdown reduced VSMC proliferation, migration, and intimal hyperplasia, and determine AIF-1 effects on si ...[more]

PMID: 18779232

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Project description:IntroductionPropionibacterium acnes, a ubiquitous skin bacterium, stimulates keratinocytes to produce a number of proinflammatory cytokines and may contribute to inflammatory acne. The aim of the study was to investigate whether P. acnes-induced proinflammatory cytokine release is mediated by P. acnes-induced activation of p38 mitogen-activated protein kinase (p38 MAPK or p38) in human keratinocytes.MethodsImmunohistochemistry was used to evaluate p38 phosphorylation in human skin samples with or without acne. Primary human keratinocytes and epidermal skin equivalents were exposed to viable P. acnes. Phosphorylation of MAPKs without or with p38 inhibitors was examined by Western blot and cytokine secretion was detected by Enzyme-Linked Immunosorbent Assay (ELISA).ResultsIncreased levels of phospho-p38 were observed in human acne lesions, predominantly in follicular and perifollicular keratinocytes. Exposure of cultured human keratinocytes to viable P. acnes resulted in phosphorylation of multiple members of the MAPK family, including rapid and transient activation of p38 and extracellular signal-related kinase (ERK1/2) and relatively slow but sustained activation of c-Jun N-terminal kinases (JNK1/2). Viable P. acnes induced the secretion of interleukin-1α (IL-1α), tumor necrosis factor-α (TNF-α), and IL-8 from human keratinocytes. The phosphorylation of p38 (phospho-p38) and the secretion of cytokines induced by P. acnes in cultured keratinocytes were inhibited by SB203580, a p38α/β inhibitor. Furthermore, SCIO-469, a selective inhibitor of p38α, showed similar effects in cultured keratinocytes. Topical treatment of SCIO-469 inhibited the P. acnes-induced phospho-p38 and cytokine secretion in human epidermal equivalents.ConclusionThe data demonstrate that P. acnes induces p38-dependent inflammatory responses in keratinocytes, and suggest that p38 may play an important role in the pathogenesis of inflammatory acne.FundingJohnson & Johnson.

Project description:Objective- Dysregulated proliferation of vascular smooth muscle cells (VSMC) plays an essential role in neointimal hyperplasia. CD36 functions critically in atherogenesis and thrombosis. We hypothesize that CD36 regulates VSMC proliferation and contributes to the development of obstructive vascular diseases. Approach and Results- We found by immunofluorescent staining that CD36 was highly expressed in human vessels with obstructive diseases. Using guidewire-induced carotid artery injury and shear stress-induced intima thickening models, we compared neointimal hyperplasia in Apoe-/-, Cd36-/- /Apoe-/-, and CD36 specifically deleted in VSMC (VSMC cd36-/-) mice. CD36 deficiency, either global or VSMC-specific, dramatically reduced injury-induced neointimal thickening. Correspondingly, carotid artery blood flow was significantly increased in Cd36-/- /Apoe-/- compared with Apoe-/- mice. In cultured VSMCs from thoracic aorta of wild-type and Cd36-/- mice, we found that loss of CD36 significantly decreased serum-stimulated proliferation and increased cell populations in S phase, suggesting that CD36 is necessary for VSMC S/G2-M-phase transition. Treatment of VSMCs with a TSR (thrombospondin type 1 repeat) peptide significantly increased wild-type, but not Cd36-/- VSMC proliferation. TSR or serum treatment significantly increased cyclin A expression in wild-type, but not in Cd36-/- VSMCs. STAT3 (signal transducer and activator of transcription), which reportedly enhances both VSMC differentiation and maturation, was higher in Cd36-/- VSMCs. CD36 deficiency significantly decreased expression of Col1A1 (type 1 collagen A1 chain) and TGF-?1 (transforming growth factor beta 1), and increased expression of contractile proteins, including calponin 1 and smooth muscle ? actin, and dramatically increased cell contraction. Conclusions- CD36 promotes VSMC proliferation via upregulation of cyclin A expression that contributes to the development of neointimal hyperplasia, collagen deposition, and obstructive vascular diseases.

Project description:BackgroundThe microbiome has a functional role in a number of inflammatory processes and disease states. While neointimal hyperplasia development has been linked to inflammation, a direct role of the microbiota in neointimal hyperplasia has not yet been established. Germ-free (GF) mice are an invaluable model for studying causative links between commensal organisms and the host. We hypothesized that GF mice would exhibit altered neointimal hyperplasia following carotid ligation compared to conventionally raised (CONV-R) mice.MethodsTwenty-week-old male C57BL/6 GF mice underwent left carotid ligation under sterile conditions. Maintenance of sterility was assessed by cultivation and 16S rRNA qPCR of stool. Neointimal hyperplasia was assessed by morphometric and histologic analysis of arterial sections after 28 days. Local arterial cell proliferation and inflammation was assessed by immunofluorescence for Ki67 and inflammatory cell markers at five days. Systemic inflammation was assessed by multiplex immunoassays of serum. CONV-R mice treated in the same manner served as the control cohort. GF and CONV-R mice were compared using standard statistical methods.ResultsAll GF mice remained sterile during the entire study period. Twenty-eight days after carotid ligation, CONV-R mice had significantly more neointimal hyperplasia development compared to GF mice, as assessed by intima area, media area, intima+media area, and intima area/(intima+media) area. The collagen content of the neointimal lesions appeared qualitatively similar on Masson's trichrome staining. There was significantly reduced Ki67 immunoreactivity in the media and adventitia of GF carotid arteries 5 days after ligation. GF mice also had increased arterial infiltration of anti-inflammatory M2 macrophages compared to CONV-R mouse arteries and a reduced proportion of mature neutrophils. GF mice had significantly reduced serum IFN-?-inducible protein (IP)-10 and MIP-2 5 days after carotid ligation, suggesting a reduced systemic inflammatory response.ConclusionsGF mice have attenuated neointimal hyperplasia development compared to CONV-R mice, which is likely related to altered kinetics of wound healing and acute inflammation. Recognizing the role of commensals in the regulation of arterial remodeling will provide a deeper understanding of the pathophysiology of restenosis and support strategies to treat or reduce restenosis risk by manipulating microbiota.

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Inhibition of allograft inflammatory factor-1 expression reduces development of neointimal hyperplasia and p38 kinase activity.

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Inhibition of allograft inflammatory factor-1 expression reduces development of neointimal hyperplasia and p38 kinase activity.

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