Efficacy of radiotherapy in combined treatment of hepatocellular carcinoma patients with portal vein tumor thrombus: a real-world study.

BACKGROUND AND AIMS: Hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) has an extremely poor prognosis. A previous study proved that low-dose radiotherapy (RT) could prolong the prognosis of HCC patients with PVTT. This study aims to explore the sensitivity of PVTT to RT treatment. METHODS: Patients were selected based on imaging diagnosis of HCC accompanied by PVTT and received combined treatment of radiotherapy, antiangiogenic drugs and immune checkpoint inhibitors, followed by hepatectomy or liver transplantation from January 2019 to August 2022. The efficacy was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines and pathological assessment. The sensitivity of tumor cells to the treatment was compared between the primary tumor (PT)and PVTT by analyzing their residual tumor and pathologic complete remission (PCR) incidence. RESULTS: Data from 14 patients were collected in the study. After combined treatment, the size of PVTT decreased more significantly than that of the primary tumor in the imaging study (p < 0.05). The residual cancer was significantly more restrictive than that of primary tumor in paired patients based on pathological measurement (p = 0.008). The PCR incidence of the primary tumor (21.42%) was significantly lower (p = 0.008) than that of PVTT in the pathologic study (78.57%). CONCLUSION: PVTT is more sensitive to radiotherapy treatment than the primary tumor in patients with HCC. This combination therapy might be an effective option as a downstaging therapy for patients with HCC with PVTT.

Selenium uptake, translocation, subcellular distribution and speciation in winter wheat in response to phosphorus application combined with three types of selenium fertilizer.

BACKGROUND: Selenium (Se) deficiency causes a series of health disorders in humans, and Se concentrations in the edible parts of crops can be improved by altering exogenous Se species. However, the uptake, transport, subcellular distribution and metabolism of selenite, selenate and SeMet (selenomethionine) under the influence of phosphorus (P) has not been well characterized. RESULTS: The results showed that increasing the P application rate enhanced photosynthesis and then increased the dry matter weight of shoots with selenite and SeMet treatment, and an appropriate amount of P combined with selenite treatment increased the dry matter weight of roots by enhancing root growth. With selenite treatment, increasing the P application rate significantly decreased the concentration and accumulation of Se in roots and shoots. P1 decreased the Se migration coefficient, which could be attributed to the inhibited distribution of Se in the root cell wall, but increased distribution of Se in the root soluble fraction, as well as the promoted proportion of SeMet and MeSeCys (Se-methyl-selenocysteine) in roots. With selenate treatment, P0.1 and P1 significantly increased the Se concentration and distribution in shoots and the Se migration coefficient, which could be attributed to the enhanced proportion of Se (IV) in roots but decreased proportion of SeMet in roots. With SeMet treatment, increasing the P application rate significantly decreased the Se concentration in shoots and roots but increased the proportion of SeCys2 (selenocystine) in roots. CONCLUSION: Compared with selenate or SeMet treatment, treatment with an appropriate amount of P combined with selenite could promote plant growth, reduce Se uptake, alter Se subcellular distribution and speciation, and affect Se bioavailability in wheat.

Mitochondrial damage-induced abnormal glucose metabolism with ageing in the hippocampus of APP/PS1 mice.

INTRODUCTION: Accumulation of ß-amyloid (Aß) in neurons of patients with Alzheimer's disease (AD) inhibits the activity of key enzymes in mitochondrial metabolic pathways, triggering mitochondrial dysfunction, which plays an important role in the onset and development of AD. Mitophagy is a process whereby dysfunctional or damaged mitochondria are removed from the cell. Aberrant mitochondrial metabolism may hinder mitophagy, promote autophagosome accumulation, and lead to neuronal death. OBJECTIVES: The aim of this experiment is to explore the mechanism of neuronal mitochondria damage in the hippocampus of different age APP/PS1 double transgenic AD mice, and to explore the related metabolites and metabolic pathways for further understanding of the pathogenesis, so as to provide new ideas and strategies for the treatment of AD. METHODS: In this study, 24 APP/PS1(APPswe/PSEN1dE9) mice were divided into 3, 6, 9, and 12-month-old groups, and 6-month-old wild-type C57BL/6 mice were as controls. The Morris water maze test was used to evaluate learning and memory. Levels of Aß were detected by immunohistochemistry. Electron microscopy was used to observe mitochondrial damage and autophagosome accumulation. Western blot was for measuring LC3, P62, PINK1, Parkin, Miro1, and Tom 20 protein expression levels. Gas chromatography coupled with mass spectrometry was used to screen differentially abundant metabolites. RESULTS: The results showed that with the increase of age in APP/PS1 mice, cognitive impairment, hippocampal neuron mitochondrial damage, and autophagosome accumulation all increased. Furthermore, enhanced mitophagy and impaired mitochondrial clearance leading to metabolic abnormalities were observed with ageing in APP/PS1 mouse hippocampus. Especially, abnormal accumulation of succinic acid and citric acid in the Krebs cycle was observed. CONCLUSION: This study investigated the abnormal glucose metabolism associated with age-related damage to mitochondria in the hippocampus of APP/PS1 mice. These findings provide new insights into the pathogenesis of AD.

Raltitrexed enhanced antitumor effect of anlotinib in human esophageal squamous carcinoma cells on proliferation, invasiveness, and apoptosis.

BACKGROUND: Anlotinib is a multi-targeted receptor tyrosine kinase inhibitor (TKI) which has exhibited encouraging clinical activity in advanced non-small cell lung cancer (NSCLC) and soft tissue sarcoma. Raltitrexed is well known to be effective in the treatment of colorectal cancer in China. The present study aims to investigate the combinatory antitumor effect of anlotinib and raltitrexed on human esophageal squamous carcinoma cells and further explore the molecular mechanisms in vitro. METHODS: Human esophageal squamous cell lines KYSE-30 and TE-1 were treated with anlotinib or raltitrexed, or both, then cell proliferation was measured by MTS and colony formation assay; cell migration and invasion were detected by wound-healing and transwell assays; cell apoptosis rate was studied by flow cytometry and the transcription of apoptosis-associated proteins were monitored by quantitative polymerase chain reaction (qPCR) analysis. Finally, western blot was performed to check phosphorylation of apoptotic proteins after treatment. RESULTS: Treatment with raltitrexed and anlotinib showed enhanced inhibitory effects on cell proliferation, migration and invasiveness compared with raltitrexed or anlotinib monotherapy. Meanwhile, raltitrexed combined with anlotinib strongly increased cell apoptosis percentage. Moreover, the combined treatment down-regulated mRNA level of the anti-apoptotic protein Bcl-2 and invasiveness-associated protein matrix metalloproteinases-9 (MMP-9), while up-regulated pro-apoptotic Bax and caspase-3 transcription. Western blotting showed that the combination of raltitrexed and anlotinib could inhibit the expression of phosphorylated Akt (p-Akt), Erk (p-Erk) and MMP-9. CONCLUSIONS: This study indicated that raltitrexed enhanced the antitumor effects of anlotinib on human ESCC cells by down-regulating phosphorylation of Akt and Erk, providing a novel treatment option for patients with esophageal squamous cell carcinoma (ESCC).

Temporal dynamics of soil dissolved organic carbon in temperate forest managed by prescribed burning in Northeast China.

Dissolved organic carbon (DOC) is an important function of soil organic carbon and sensitive to environmental disturbance. Few studies have explored the variations in soil DOC dynamics and effects on soil physicochemical properties following prescribed burnings. In this study, Pinus koraiensis plantation forests in Northeast China were selected and subjected to prescribed burning in early November 2018. Soil DOC and different soil physicochemical and biological properties in the 0-10 cm and 10-20 cm soil layers were sampled six times within two years after a prescribed burning. In this study, some soil physicochemical (SOC, TN, and ST) and microbial biomass properties (MBC) recovered within two years after a prescribed burning. Compared to the unburned control stands, the post-fire soil DOC concentrations in the upper and lower soil layers increased by 16% and 12%, respectively. Soil DOC concentrations varied with sampling time, and peaked one year after the prescribed burning. Our results showed that soil chemical properties (NH4+-N and pH) rather than biological properties (microbial biomass) were the main driving factors for changes in post-fire soil DOC concentrations. Current study provides an important reference for post-fire and seasonal soil C cycling in plantation forests of Northeast China.

Risk of Immune-Related Pneumonitis with PD-1/PD-L1 Inhibitors in Different Cancer Types and Treatment Regimens: A Systematic Review and Meta-Analysis of 22 Randomized Controlled Trials.

BACKGROUND: Pneumonitis, the specific toxicity associated with PD-1/PD-L1 inhibitors, is severe and potentially life-threatening, and its incidence and severity are poorly understood among different tumor types or treatment methods. This meta-analysis was performed to compare the incidence and severity of pneumonitis among different tumor types and treatment regimens. METHODS: MEDLINE and Embase were retrieved until September 2021. Meta-analysis of the risk of pneumonitis was calculated using a fixed-effect model. Pooled analysis of the incidence of pneumonitis in different tumor types was performed using a metaprop function. RESULTS: Twenty two randomized controlled trials (RCTs) (n = 10,700) were included for pool analysis, and eighteen RCTs (n = 8,852) were eligible for meta-analysis. For all-grade pneumonitis, the risk of the combination therapy (PD-1/PD-L1 plus CTLA-4 inhibitor) was 3.62 times significantly higher than that of monotherapy, and 4.06 and 1.78 times significantly higher than that of chemotherapy and placebo than monotherapy. The incidence of pneumonitis was not significantly different between PD-1/PD-L1 inhibitor versus ipilimumab or between low doses versus high doses. For high-grade (grade ≥3) pneumonitis, the risk in PD-1/PD-L1 inhibitors alone was 3.62 times significantly higher than chemotherapy. No significant difference was found in the incidence of pneumonitis between combination versus monotherapy, monotherapy versus placebo, combination versus ipilimumab alone, monotherapy versus ipilimumab alone, or low doses versus high doses. CONCLUSIONS: Compared with chemotherapy, PD-1/PD-L1 inhibitor monotherapy may cause more treatment-related pneumonitis. Increasing the dose of PD-1/PD-L1 inhibitor does not significantly increase the incidence of pneumonitis. Compared with the monotherapy, combination therapy does not increase the incidence of pneumonitis significantly.

Hexarelin attenuates abdominal aortic aneurysm formation by inhibiting SMC phenotype switch and inflammasome activation.

Hexarelin, a synthetic growth hormone-releasing peptide, is shown to be protective in cardiovascular diseases such as myocardial infraction and atherosclerosis. However, the functional role of hexarelin in abdominal aortic aneurysm (AAA) remains undefined. The present study determined the effect of hexarelin administration (200 µg/kg twice per day) in a mouse model of elastase-induced abdominal aortic aneurysm. Echocardiography and in situ pictures showed hexarelin decreased infrarenal aorta diameter. Histology staining showed elastin degradation was improved in hexarelin-treated group. Hexarelin rescued smooth muscle cell contractile phenotype with increased α-SMA and decreased MMP2. Furthermore, hexarelin inhibited inflammatory cell infiltration, NLRP3 inflammasome activation and IL-18 production. Particularly, hexarelin suppressed NF-κB signaling pathway which is a key initiator of inflammatory response. These results demonstrated that hexarelin attenuated AAA development by inhibiting SMC phenotype switch and NF-κB signaling mediated inflammatory response.

Roles of mTOR in thoracic aortopathy understood by complex intracellular signaling interactions.

Thoracic aortopathy-aneurysm, dissection, and rupture-is increasingly responsible for significant morbidity and mortality. Advances in medical genetics and imaging have improved diagnosis and thus enabled earlier prophylactic surgical intervention in many cases. There remains a pressing need, however, to understand better the underlying molecular and cellular mechanisms with the hope of finding robust pharmacotherapies. Diverse studies in patients and mouse models of aortopathy have revealed critical changes in multiple smooth muscle cell signaling pathways that associate with disease, yet integrating information across studies and models has remained challenging. We present a new quantitative network model that includes many of the key smooth muscle cell signaling pathways and validate the model using a detailed data set that focuses on hyperactivation of the mechanistic target of rapamycin (mTOR) pathway and its inhibition using rapamycin. We show that the model can be parameterized to capture the primary experimental findings both qualitatively and quantitatively. We further show that simulating a population of cells by varying receptor reaction weights leads to distinct proteomic clusters within the population, and that these clusters emerge due to a bistable switch driven by positive feedback in the PI3K/AKT/mTOR signaling pathway.

Screening of Codonopsis radix Polysaccharides with Different Molecular Weights and Evaluation of Their Immunomodulatory Activity In Vitro and In Vivo.

Polysaccharide is one of the main components of Codonopsis radix (CR) and has good immune activity. However, the immune activity of CR polysaccharides with different molecular weights has not been systematically screened. In this study, the polysaccharides of CR from Pingshun of Shanxi Province (PSDSs) were first divided into two groups using ultrafiltration: 3.3 kDa (PSDSs-1) and more than 2000 kDa (PSDSs-2). The immunomodulatory effects of PSDSs with different molecular weights were evaluated in vitro and in vivo. In vitro experimental results showed that compared with Lipopolysaccharide-induced macrophages, PSDSs-1 increased TNF-α and IL-6 levels and decreased IL-10. Meanwhile, PSDSs-2 showed the opposite effect, indicating the difference in pro- and anti-inflammatory activities of PSDSs with different molecular weights. The immunosuppressive model of cyclophosphamide proved that PSDSs have immune-promoting function, with PSDSs-1 exhibiting a better effect than PSDSs-2. In vitro and in vivo experiments illustrated the complexity of PSDS immunomodulation. Further research on the functions of PSDs with different molecular weights is needed to lay a foundation for their classification and application.

Developmental origins of mechanical homeostasis in the aorta.

BACKGROUND: Mechanical homeostasis promotes proper aortic structure and function. Pathological conditions may arise, in part, from compromised or lost homeostasis. There is thus a need to quantify the homeostatic state and when it emerges. Here we quantify changes in mechanical loading, geometry, structure, and function of the murine aorta from the late prenatal period into maturity. RESULTS: Our data suggest that a homeostatic set-point is established by postnatal day P2 for the flow-induced shear stress experienced by endothelial cells; this value deviates from its set-point from P10 to P21 due to asynchronous changes in mechanical loading (flow, pressure) and geometry (radius, wall thickness), but is restored thereafter consistent with homeostasis. Smooth muscle contractility also decreases during this period of heightened matrix deposition but is also restored in maturity. The pressure-induced mechanical stress experienced by intramural cells initially remains low despite increasing blood pressure, and then increases while extracellular matrix accumulates. CONCLUSIONS: These findings suggest that cell-level mechanical homeostasis emerges soon after birth to allow mechanosensitive cells to guide aortic development, with deposition of matrix after P2 increasingly stress shielding intramural cells. The associated tissue-level set-points that emerge for intramural stress can be used to assess and model the aorta that matures biomechanically by P56.

Endothelial Cell-Derived Interleukin-18 Released During Ischemia Reperfusion Injury Selectively Expands T Peripheral Helper Cells to Promote Alloantibody Production.

BACKGROUND: Ischemia reperfusion injury (IRI) predisposes to the formation of donor-specific antibodies, a factor contributing to chronic rejection and late allograft loss. METHODS: We describe a mechanism underlying the correlative association between IRI and donor-specific antibodies by using humanized models and patient specimens. RESULTS: IRI induces immunoglobulin M-dependent complement activation on endothelial cells that assembles an NLRP3 (NOD-like receptor pyrin domain-containing protein 3) inflammasome via a Rab5-ZFYVE21-NIK axis and upregulates ICOS-L (inducible costimulator ligand) and PD-L2 (programmed death ligand 2). Endothelial cell-derived interleukin-18 (IL-18) selectively expands a T-cell population (CD4+CD45RO+PD-1hiICOS+CCR2+CXCR5-) displaying features of recently described T peripheral helper cells. This population highly expressed IL-18R1 and promoted donor-specific antibodies in response to IL-18 in vivo. In patients with delayed graft function, a clinical manifestation of IRI, these cells were Ki-67+IL-18R1+ and could be expanded ex vivo in response to IL-18. CONCLUSIONS: IRI promotes elaboration of IL-18 from endothelial cells to selectively expand alloreactive IL-18R1+ T peripheral helper cells in allograft tissues to promote donor-specific antibody formation.

Complement Membrane Attack Complexes Assemble NLRP3 Inflammasomes Triggering IL-1 Activation of IFN-γ-Primed Human Endothelium.

RATIONALE: Complement activation contributes to multiple immune-mediated pathologies. In late allograft failure, donor-specific antibody deposits complement membrane attack complexes (MAC) on graft endothelial cells (ECs), substantially increasing their immunogenicity without causing lysis. Internalized MAC stabilize NIK (NF-κB [nuclear factor kappa-light-chain-enhancer of activated B cells]-inducing kinase) protein on Rab5+MAC+ endosomes, activating noncanonical NF-κB signaling. However, the link to increased immunogenicity is unclear. OBJECTIVE: To identify mechanisms by which alloantibody and internalized MAC activate ECs to enhance their ability to increase T-cell responses. METHODS AND RESULTS: In human EC cultures, internalized MAC also causes NLRP3 (NOD-like receptor family pyrin domain containing 3) translocation from endoplasmic reticulum to Rab5+MAC+NIK+ endosomes followed by endosomal NIK-dependent inflammasome assembly. Cytosolic NIK, stabilized by LIGHT (lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells), does not trigger inflammasome assembly, and ATP-triggered inflammasome assembly does not require NIK. IFN-γ (interferon-γ) primes EC responsiveness to MAC by increasing NLRP3, pro-caspase 1, and gasdermin D expression. NIK-activated noncanonical NF-κB signaling induces pro-IL (interleukin)-1ß expression. Inflammasome processed pro-IL-1ß, and gasdermin D results in IL-1ß secretion that increases EC immunogenicity through IL-1 receptor signaling. Activation of human ECs lining human coronary artery grafts in immunodeficient mouse hosts by alloantibody and complement similarly depends on assembly of an NLRP3 inflammasome. Finally, in renal allograft biopsies showing chronic rejection, caspase-1 is activated in C4d+ ECs of interstitial microvessels, supporting the relevance of the cell culture findings. CONCLUSIONS: In response to antibody-mediated complement activation, IFN-γ-primed human ECs internalize MAC, triggering both endosomal-associated NIK-dependent NLRP3 inflammasome assembly and IL-1 synthesis, resulting in autocrine/paracrine IL-1ß-mediated increases in EC immunogenicity. Similar responses may underlie other complement-mediated pathologies.

Caveolin-1 Regulates Atherogenesis by Attenuating Low-Density Lipoprotein Transcytosis and Vascular Inflammation Independently of Endothelial Nitric Oxide Synthase Activation.

BACKGROUND: Atherosclerosis is driven by synergistic interactions between pathological, biomechanical, inflammatory, and lipid metabolic factors. Our previous studies demonstrated that absence of caveolin-1 (Cav1)/caveolae in hyperlipidemic mice strongly inhibits atherosclerosis, which was attributed to activation of endothelial nitric oxide (NO) synthase (eNOS) and increased production of NO and reduced inflammation and low-density lipoprotein trafficking. However, the contribution of eNOS activation and NO production in the athero-protection of Cav1 and the exact mechanisms by which Cav1/caveolae control the pathogenesis of diet-induced atherosclerosis are still not clear. METHODS: Triple-knockout mouse lacking expression of eNOS, Cav1, and Ldlr were generated to explore the role of NO production in Cav1-dependent athero-protective function. The effects of Cav1 on lipid trafficking, extracellular matrix remodeling, and vascular inflammation were studied both in vitro and in vivo with a mouse model of diet-induced atherosclerosis. The expression of Cav1 and distribution of caveolae regulated by flow were analyzed by immunofluorescence staining and transmission electron microscopy. RESULTS: We found that absence of Cav1 significantly suppressed atherogenesis in Ldlr-/-eNOS-/- mice, demonstrating that athero-suppression is independent of increased NO production. Instead, we find that the absence of Cav1/caveolae inhibited low-density lipoprotein transport across the endothelium and proatherogenic fibronectin deposition and disturbed flow-mediated endothelial cell inflammation. Consistent with the idea that Cav1/caveolae may play a role in early flow-dependent inflammatory priming, distinct patterns of Cav1 expression and caveolae distribution were observed in athero-prone and athero-resistant areas of the aortic arch even in wild-type mice. CONCLUSIONS: These findings support a role for Cav1/caveolae as a central regulator of atherosclerosis that links biomechanical, metabolic, and inflammatory pathways independently of endothelial eNOS activation and NO production.

miR-29a Regulates the Proliferation and Migration of Human Arterial Smooth Muscle Cells in Arteriosclerosis Obliterans of the Lower Extremities.

BACKGROUND: The molecular mechanisms underlying the contribution of human arterial smooth muscle cells (HASMCs), one of the most important components of the arterial wall, to the pathogenesis of arteriosclerosis obliterans (ASO) remain elusive. METHODS: The expression levels of miR-29a in arterial walls were analyzed via real-time-polymerase chain reaction. An ASO cell model was established to investigate the expression of miR-29a on HASMCs. The interaction between miR-29a and platelet-derived growth factor receptor B (PDGFRB) was detected by luciferase reporter assay, and the alteration of the expression of PDGFRB was determined in platelet-derived growth factor­BB (PDGF-BB)-stimulated HASMCs transfected with miR-NC, miR-29a mimics, and miR-29a inhibitors. Further, HASMCs cell proliferation was investigated by cell counting kit-8 and EdU assays, and cell migrations were evaluated by Transwell and wound closure assays. RESULTS: The expression of miR-29a was remarkably downregulated in the arterial walls of ASO patients compared with normal arterial walls. Furthermore, expression of miR-29a in HASMCs under PDGF-BB stimulation was lower than vehicle control. PDGFRB was identified as a target of miR-29a in HASMCs, and miR-29a inhibited the proliferation and migration in PDGF-BB-induced HASMCs, via regulating the expression of PDGFRB. CONCLUSION: This study showed that miR-29a is downregulated in the arterial wall of ASO patients, as well as in the PDGF-BB-stimulated HASMCs. This alteration of miR-29a could upregulate target genes PDGFRB and inhibits the proliferation and migration of HASMCs. These findings discovered new mechanisms of ASO pathogenesis, and the miR-29a/PDGFRB axis could serve as potential therapy target of ASO.

Deficient Circumferential Growth Is the Primary Determinant of Aortic Obstruction Attributable to Partial Elastin Deficiency.

OBJECTIVE: Williams syndrome is characterized by obstructive aortopathy attributable to heterozygous loss of ELN, the gene encoding elastin. Lesions are thought to result primarily from excessive smooth muscle cell (SMC) proliferation and consequent medial expansion, although an initially smaller caliber and increased stiffness of the aorta may contribute to luminal narrowing. The relative contributions of such abnormalities to the obstructive phenotype had not been defined. APPROACH AND RESULTS: We quantified determinants of luminal stenosis in thoracic aortas of Eln-/- mice incompletely rescued by human ELN. Moderate obstruction was largely because of deficient circumferential growth, most prominently of ascending segments, despite increased axial growth. Medial thickening was evident in these smaller diameter elastin-deficient aortas, with medial area similar to that of larger diameter control aortas. There was no difference in cross-sectional SMC number between mutant and wild-type genotypes at multiple stages of postnatal development. Decreased elastin content was associated with medial fibrosis and reduced aortic distensibility because of increased structural stiffness but preserved material stiffness. Elastin-deficient SMCs exhibited greater contractile-to-proliferative phenotypic modulation in vitro than in vivo. We confirmed increased medial collagen without evidence of increased medial area or SMC number in a small ascending aorta with thickened media of a Williams syndrome subject. CONCLUSIONS: Deficient circumferential growth is the predominant mechanism for moderate obstructive aortic disease resulting from partial elastin deficiency. Our findings suggest that diverse aortic manifestations in Williams syndrome result from graded elastin content, and SMC hyperplasia causing medial expansion requires additional elastin loss superimposed on ELN haploinsufficiency.

mTOR (Mechanistic Target of Rapamycin) Inhibition Decreases Mechanosignaling, Collagen Accumulation, and Stiffening of the Thoracic Aorta in Elastin-Deficient Mice.

OBJECTIVE: Elastin deficiency because of heterozygous loss of an ELN allele in Williams syndrome causes obstructive aortopathy characterized by medial thickening and fibrosis and consequent aortic stiffening. Previous work in Eln-null mice with a severe arterial phenotype showed that inhibition of mTOR (mechanistic target of rapamycin), a key regulator of cell growth, lessened the aortic obstruction but did not prevent early postnatal death. We investigated the effects of mTOR inhibition in Eln-null mice partially rescued by human ELN that manifest a less severe arterial phenotype and survive long term. APPROACH AND RESULTS: Thoracic aortas of neonatal and juvenile mice with graded elastin deficiency exhibited increased signaling through both mTOR complex 1 and 2. Despite lower predicted wall stress, there was increased phosphorylation of focal adhesion kinase, suggestive of greater integrin activation, and increased transforming growth factor-ß-signaling mediators, associated with increased collagen expression. Pharmacological blockade of mTOR by rapalogs did not improve luminal stenosis but reduced mechanosignaling (in delayed fashion after mTOR complex 1 inhibition), medial collagen accumulation, and stiffening of the aorta. Rapalog administration also retarded somatic growth, however, and precipitated neonatal deaths. Complementary, less-toxic strategies to inhibit mTOR via altered growth factor and nutrient responses were not effective. CONCLUSIONS: In addition to previously demonstrated therapeutic benefits of rapalogs decreasing smooth muscle cell proliferation in the absence of elastin, we find that rapalogs also prevent aortic fibrosis and stiffening attributable to partial elastin deficiency. Our findings suggest that mTOR-sensitive perturbation of smooth muscle cell mechanosensing contributes to elastin aortopathy.

Complement membrane attack complexes activate noncanonical NF-κB by forming an Akt+ NIK+ signalosome on Rab5+ endosomes.

Complement membrane attack complexes (MACs) promote inflammatory functions in endothelial cells (ECs) by stabilizing NF-κB-inducing kinase (NIK) and activating noncanonical NF-κB signaling. Here we report a novel endosome-based signaling complex induced by MACs to stabilize NIK. We found that, in contrast to cytokine-mediated activation, NIK stabilization by MACs did not involve cIAP2 or TRAF3. Informed by a genome-wide siRNA screen, instead this response required internalization of MACs in a clathrin-, AP2-, and dynamin-dependent manner into Rab5(+)endosomes, which recruited activated Akt, stabilized NIK, and led to phosphorylation of IκB kinase (IKK)-α. Active Rab5 was required for recruitment of activated Akt to MAC(+) endosomes, but not for MAC internalization or for Akt activation. Consistent with these in vitro observations, MAC internalization occurred in human coronary ECs in vivo and was similarly required for NIK stabilization and EC activation. We conclude that MACs activate noncanonical NF-κB by forming a novel Akt(+)NIK(+) signalosome on Rab5(+) endosomes.

Inhibition of the mTOR pathway in abdominal aortic aneurysm: implications of smooth muscle cell contractile phenotype, inflammation, and aneurysm expansion.

The development of effective pharmacological treatment of abdominal aortic aneurysm (AAA) potentially offers great benefit to patients with preaneurysmal aortic dilation by slowing the expansion of aneurysms and reducing the need for surgery. To date, therapeutic targets for slowing aortic dilation have had low efficacy. Thus, in this study, we aim to elucidate possible mechanisms driving aneurysm progression to identify potential targets for pharmacological intervention. We demonstrate that mechanistic target of rapamycin (mTOR) signaling is overactivated in aortic smooth muscle cells (SMCs), which contributes to murine AAA. Rapamycin, a typical mTOR pathway inhibitor, dramatically limits the expansion of the abdominal aorta following intraluminal elastase perfusion. Furthermore, reduction of aortic diameter is achieved by inhibition of the mTOR pathway, which preserves and/or restores the contractile phenotype of SMCs and downregulates macrophage infiltration, matrix metalloproteinase expression, and inflammatory cytokine production. Taken together, these results highlight the important role of the mTOR cascade in aneurysm progression and the potential application of rapamycin as a therapeutic candidate for AAA.NEW & NOTEWORTHY This study provides novel observations that mechanistic target of rapamycin (mTOR) signaling is overactivated in aortic smooth muscle cells and contributes to mouse abdominal aortic aneurysm (AAA) and that rapamycin protects against aneurysm development. Our data highlight the importance of preservation and/or restoration of the smooth muscle cell contractile phenotype and reduction of inflammation by mTOR inhibition in AAA.

Interferon-γ-mediated allograft rejection exacerbates cardiovascular disease of hyperlipidemic murine transplant recipients.

RATIONALE: Transplantation, the most effective therapy for end-stage organ failure, is markedly limited by early-onset cardiovascular disease (CVD) and premature death of the host. The mechanistic basis of this increased CVD is not fully explained by known risk factors. OBJECTIVE: To investigate the role of alloimmune responses in promoting CVD of organ transplant recipients. METHODS AND RESULTS: We established an animal model of graft-exacerbated host CVD by combining murine models of atherosclerosis (apolipoprotein E-deficient recipients on standard diet) and of intra-abdominal graft rejection (heterotopic cardiac transplantation without immunosuppression). CVD was absent in normolipidemic hosts receiving allogeneic grafts and varied in severity among hyperlipidemic grafted hosts according to recipient-donor genetic disparities, most strikingly across an isolated major histocompatibility complex class II antigen barrier. Host disease manifested as increased atherosclerosis of the aorta that also involved the native coronary arteries and new findings of decreased cardiac contractility, ventricular dilatation, and diminished aortic compliance. Exacerbated CVD was accompanied by greater levels of circulating cytokines, especially interferon-γ and other Th1-type cytokines, and showed both systemic and intralesional activation of leukocytes, particularly T-helper cells. Serological neutralization of interferon-γ after allotransplantation prevented graft-related atherosclerosis, cardiomyopathy, and aortic stiffening in the host. CONCLUSIONS: Our study reveals that sustained activation of the immune system because of chronic allorecognition exacerbates the atherogenic diathesis of hyperlipidemia and results in de novo cardiovascular dysfunction in organ transplant recipients.

Pharmacologically Improved Contractility Protects Against Aortic Dissection in Mice With Disrupted Transforming Growth Factor-ß Signaling Despite Compromised Extracellular Matrix Properties.

OBJECTIVE: Transforming growth factor-beta is a pleiotropic cytokine having diverse roles in vascular morphogenesis, homeostasis, and pathogenesis. Altered activity of and signaling through transforming growth factor-beta has been implicated in thoracic aortic aneurysms and dissections, conditions characterized by a reduced structural integrity of the wall that associates with altered biomechanics and mechanobiology. We quantify and contrast the passive and active biaxial biomechanical properties of the ascending and proximal descending thoracic aorta in a mouse model of altered transforming growth factor-beta signaling, with and without treatment with rapamycin. APPROACH AND RESULTS: Postnatal disruption of the gene (Tgfbr2) that codes the type II transforming growth factor-beta receptor compromises vessel-level contractility and elasticity. Daily treatment with rapamycin, a mechanistic target of rapamycin inhibitor that protects against aortic dissection in these mice, largely preserves or restores the contractile function while the passive properties remain compromised. Importantly, this increased smooth muscle contractility protects an otherwise vulnerable aortic wall from pressure-induced intramural delaminations in vitro. CONCLUSIONS: Notwithstanding the protection afforded by rapamycin in vivo and in vitro, the residual mechanical dysfunctionality suggests a need for caution if rapamycin is to be considered as a potential therapeutic. There is a need for in vivo evaluations in cases of increased hemodynamic loading, including hypertension or extreme exercise, which could unduly stress a structurally vulnerable aortic wall. Given these promising early results, however, such studies are clearly warranted.