Predicting post-resection recurrence by integrating imaging-based surrogates of distinct vascular patterns of hepatocellular carcinoma

Background & Aims

Distinct vascular patterns, including microvascular invasion (MVI) and vessels encapsulating tumour clusters (VETC), are associated with poor outcomes of hepatocellular carcinoma (HCC). Imaging surrogates of these vascular patterns potentially help to predict post-resection recurrence. Herein, a prognostic model integrating imaging-based surrogates of these distinct vascular patterns was developed to predict postoperative recurrence-free survival (RFS) in patients with HCC.

Methods

Clinico-radiological data of 1,285 patients with HCC from China undergoing surgical resection were retrospectively enrolled from seven medical centres between 2014 and 2020. A prognostic model using clinical data and imaging-based surrogates of MVI and VETC patterns was developed (n = 297) and externally validated (n = 373) to predict RFS. The surrogates (i.e. MVI and VETC scores) were individually built from preoperative computed tomography using two independent cohorts (n = 360 and 255). Whether the model's stratification was associated with postoperative recurrence following anatomic resection was also evaluated.

Results

The MVI and VETC scores demonstrated effective performance in their respective training and validation cohorts (AUC: 0.851-0.883 for MVI and 0.834-0.844 for VETC). The prognostic model incorporating serum alpha-foetoprotein, tumour multiplicity, MVI score, and VETC score achieved a C-index of 0.748-0.764 for the developing and external validation cohorts and generated three prognostically distinct strata. For patients at model-predicted medium risk, anatomic resection was associated with improved RFS (p <0.05). By contrast, anatomic resection had no impact on RFS in patients at model-predicted low or high risk (both p >0.05).

Conclusions

The proposed model integrating imaging-based surrogates of distinct vascular patterns enabled accurate prediction for RFS. It can potentially be used to identify HCC surgical candidates who may benefit from anatomic resection.

Impact and implications

MVI and VETC are distinct vascular patterns of HCC associated with aggressive biological behaviour and poor outcomes. Our multicentre study provided a model incorporating imaging-based surrogates of these patterns for preoperatively predicting RFS. The proposed model, which uses imaging detection to estimate the risk of MVI and VETC, offers an opportunity to help shed light on the association between tumour aggressiveness and prognosis and to support the selection of the appropriate type of surgical resection.

[Comparison of pulmonary vascular tortuosity and fractal dimension in patients with chronic thromboembolic pulmonary disease and chronic thromboembolic pulmonary hypertension]

Objective: To compare the differences in pulmonary vascular morphological parameters between patients with chronic thromboembolic pulmonary disease (CTEPD) and chronic thromboembolic pulmonary hypertension(CTEPH), and to explore the value of pulmonary artery morphology in the differential diagnosis of CTEPD and CTEPH. Methods: Thirty-nine patients with CTEPH [14 males, 25 females, mean age: (54.1±12.4) years] and 29 patients with CTEPD [10 males, 19 females, mean age: (51.4±18.0) years] from January 2018 to December 2020 were retrospectively included. The pulmonary artery and vein tree was segmented from the computed tomography pulmonary angiography (CTPA) images, and the morphological parameters of pulmonary vessels including the number of pulmonary arteries, pulmonary arterial tortuosity(distance metric, DM) and fractal dimension (FD), were calculated. The differences in pulmonary vascular morphological parameters between the two groups were compared, and the correlation between morphological parameters and hemodynamics was analyzed. Results: There was no significant difference in gender and age between CTEPH and CTEPD groups (χ2=0.015,P=0.904 & t=-0.729, P=0.469). The number of pulmonary arteries in CTEPH group (n=249.43±76.27) was significantly lower than that in CTEPF group (n=298.79±78.11, t=2.612, P=0.011). The pulmonary arterial tortuosity in CTEPH group (DM=1.26±0.17) was significantly higher than that in CTEPD group (DM=1.17±0.10, t=3.516, P=0.002). There was no significant difference in FD between CTEPH and CTEPD (FD=3.01±0.21 & 3.08±0.22, t=1.359, P=0.179). The number of pulmonary arteries was negatively correlated with pulmonary vascular resistance (r=-0.325, P=0.026). Pulmonary arterial tortuosity was positively correlated with mean pulmonary artery pressure (r=0.387,P=0.017), and was positively correlated with pulmonary vascular resistance (r=0.647, P<0.001). Conclusion: Pulmonary artery curvature is an important morphological parameter in differentiating CTEPH from CTEPD, and is related to mean pulmonary artery pressure and pulmonary vascular resistance.

Predicting Microvascular Invasion in Hepatocellular Carcinoma Using CT-based Radiomics Model

Background Prediction of microvascular invasion (MVI) may help determine treatment strategies for hepatocellular carcinoma (HCC). Purpose To develop a radiomics approach for predicting MVI status based on preoperative multiphase CT images and to identify MVI-associated differentially expressed genes. Materials and Methods Patients with pathologically proven HCC from May 2012 to September 2020 were retrospectively included from four medical centers. Radiomics features were extracted from tumors and peritumor regions on preoperative registration or subtraction CT images. In the training set, these features were used to build five radiomics models via logistic regression after feature reduction. The models were tested using internal and external test sets against a pathologic reference standard to calculate area under the receiver operating characteristic curve (AUC). The optimal AUC radiomics model and clinical-radiologic characteristics were combined to build the hybrid model. The log-rank test was used in the outcome cohort (Kunming center) to analyze early recurrence-free survival and overall survival based on high versus low model-derived score. RNA sequencing data from The Cancer Image Archive were used for gene expression analysis. Results A total of 773 patients (median age, 59 years; IQR, 49-64 years; 633 men) were divided into the training set (n = 334), internal test set (n = 142), external test set (n = 141), outcome cohort (n = 121), and RNA sequencing analysis set (n = 35). The AUCs from the radiomics and hybrid models, respectively, were 0.76 and 0.86 for the internal test set and 0.72 and 0.84 for the external test set. Early recurrence-free survival (P < .01) and overall survival (P < .007) can be categorized using the hybrid model. Differentially expressed genes in patients with findings positive for MVI were involved in glucose metabolism. Conclusion The hybrid model showed the best performance in prediction of MVI. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Summers in this issue.

[Self-reported quality of life in patients with coronary heart disease and analysis of the associated factors]

Objective: To investigate the quality of life and associated factors in patients with coronary heart disease (CHD) in China. Methods: A cross-sectional study of 25 provinces and cities in China was performed from June to September 2020. A questionnaire was used to collect the socio-demographic and clinical information of patients with CHD, while the European Five-dimensional Quality of Life Scale (EQ-5D) was used to assess the quality of life. Multiple linear regression model was performed to analyze the associated factors. Results: The median age of the 1 075 responders was 60 (52, 67) years, and 797 (74.1%) were men. The EQ-5D and EQ-VAS indices were 0.7 (0.5, 0.8) and 60.0 (40.0, 80.0). Among the five dimensions in the quality of life scale, the frequency of anxiety/depression was the highest (59.8%), while problems in self-care was the lowest (35.8%). In the multiple linear regression model, female, increasing age, obesity, comorbidity(ies), anxiety/depression, social media channels, and receiving the CABG therapy were associated with the lower EQ-5D index (all P<0.05). In addition, increasing age, obesity, comorbidity (ies), depression, anxiety and depression, social media channels, and receiving the CABG therapy were associated with lower EQ-VAS index (all P<0.05). Conclusion: Over half of the patients with CHD in China have a low quality of life, which is related to gender, age, obesity, treatment pathway, the presence or absence of comorbidity (ies), and psychological state. In addition to managing the adverse effects of traditional socio-demographic factors on the quality of life, clinical practices should pay attention to the psychological state of patients. Moreover, establishing a WeChat group for doctor-patient communication could improve the quality of life of CHD patients.

Preoperative Microvascular Invasion Prediction to Assist in Surgical Plan for Single Hepatocellular Carcinoma: Better Together with Radiomics

BACKGROUND

Prediction models with or without radiomic analysis for microvascular invasion (MVI) in hepatocellular carcinoma (HCC) have been reported, but the potential for model-predicted MVI in surgical planning is unclear. Therefore, we aimed to explore the effect of predicted MVI on early recurrence after anatomic resection (AR) and non-anatomic resection (NAR) to assist surgical strategies.

METHODS

Patients with a single HCC of 2-5 cm receiving curative resection were enrolled from 2 centers. Their data were used to develop (n = 230) and test (n = 219) two prediction models for MVI using clinical factors and preoperative computed tomography images. The two prediction models, clinico-radiologic model and clinico-radiologic-radiomic (CRR) model (clinico-radiologic variables + radiomic signature), were compared using the Delong test. Early recurrence based on model-predicted high-risk MVI was evaluated between AR (n = 118) and NAR (n = 85) via propensity score matching using patient data from another 2 centers for external validation.

RESULTS

The CRR model showed higher area under the curve values (0.835-0.864 across development, test, and external validation) but no statistically significant improvement over the clinico-radiologic model (0.796-0.828). After propensity score matching, difference in 2-year recurrence between AR and NAR was found in the CRR model predicted high-risk MVI group (P = 0.005) but not in the clinico-radiologic model predicted high-risk MVI group (P = 0.31).

CONCLUSIONS

The prediction model incorporating radiomics provided an accurate preoperative estimation of MVI, showing the potential for choosing the more appropriate surgical procedure between AR and NAR.

An Investigation of the Impacts of Three Anesthetic Regimens on Task-Functional Magnetic Resonance Imaging and Functional Connectivity Resting-State Functional Magnetic Resonance Imaging in Sprague Dawley and Wistar Rats

Aim: The aim of this study was to investigate basic task-functional magnetic resonance imaging (fMRI) or resting-state fMRI (rs-fMRI) results on Sprague Dawley (SD) rats and Wistar rats under three anesthetic regimens. Introduction: SD rats and Wistar rats are the two-most commonly used rat strains in medical research and neuroimaging studies. It still lacks a direct comparison of basic task-fMRI and rs-fMRI results between the Wistar rats and SD rats under different anesthetic regimens. Methods: Two rat strains and different time points were adopted to investigate task-fMRI activation and rs-fMRI functional connectivity (FC) results under three kinds of anesthetic regimens (2-2.5% isoflurane only, dexmedetomidine bolus combined with a continuous infusion, and dexmedetomidine bolus combined with 0.3-0.5% isoflurane). The electrical forepaw stimulation method and seed-based FC results were used to compare the task-fMRI brain activation and rs-fMRI FC patterns between the two rat strains. Results: The results showed that Wistar rats had more robust brain activation in task fMRI experiments while exhibiting a less specific interhemispheric FC than that of SD rats under the two dexmedetomidine anesthetic regimens. Moreover, even low-level isoflurane could significantly affect task-fMRI and rs-fMRI results in both rat strains. Conclusions: SD and Wistar rats showed different brain activations and interhemispheric FC patterns under the two dexmedetomidine anesthetic regimens. These results may serve as reference information for small-animal fMRI studies. Impact statement Our study demonstrates different stimulation-induced blood oxygen level-dependent responses and functional connectivity patterns between Sprague Dawley rats and Wistar rats under three anesthetics. This study provides some reference results for different anesthetics' effects on different rat strains in different functional magnetic resonance imaging modalities.

Effect of uniconazole and nitrogen level on lodging resistance and yield potential of maize under medium and high plant density

Lodging in maize results in grain yield reduction. This experiment investigated the effects of different application rates of the growth retardant, uniconazole (UCZ), and nitrogen (N) on medium and high maize population densities on lodging resistance and yield. UCZ was applied to maize seeds at concentrations of 0 (U₀ ) and 25 (U₂₅ ) mg kg^-1 , and three different N application rates, 0 (N₀ ), 150 (N₁₅₀ ) and 225 (N₂₂₅ ) kg ha^-1 , at plant densities of 75,000 (D₁ ) and 105,000 plants ha^-1 (D₂ ). UCZ application, different N rates and plant population density affected the lodging resistance and yield attributes of maize. The diameter, plumpness, cortex penetration and bending strengths of the internodes were enhanced with UCZ and N application at medium and high plant density, where maximum values were obtained with U₂₅ N₁₅₀ D₁ . Internode length increased in the high-density population and higher N rate, whereas UCZ reduced internode length, where maximum internode length was obtained with U₀ N₂₂₅ D₂ . Plant height, centre of gravity height, ear and height above ear-bearing node were higher with the high N rate, while UCZ reduced it significantly. UCZ, N rate and plant density enhanced lignin accumulation in the third internode and ear-bearing internode, where maximum values were obtained with U₂₅ N₁₅₀ D₁ . Yield and yield attributes were also improved by UCZ, N rate and population density. Treatment with U₂₅ N₁₅₀ D₂ significantly improved grain yield of maize compared with the other treatments.

Comparison of MRI and CT for the Prediction of Microvascular Invasion in Solitary Hepatocellular Carcinoma Based on a Non-Radiomics and Radiomics Method: Which Imaging Modality Is Better?

BACKGROUND

Computed tomography (CT) and magnetic resonance imaging (MRI) are both capable of predicting microvascular invasion (MVI) in hepatocellular carcinoma (HCC). However, which modality is better is unknown.

PURPOSE

To intraindividually compare CT and MRI for predicting MVI in solitary HCC and investigate the added value of radiomics analyses.

STUDY TYPE

Retrospective.

SUBJECTS

Included were 402 consecutive patients with HCC (training set:validation set = 300:102).

FIELD STRENGTH/SEQUENCE

T2-weighted, diffusion-weighted, and contrast-enhanced T1-weighted imaging MRI at 3.0T and contrast-enhanced CT.

ASSESSMENT

CT- and MR-based radiomics signatures (RS) were constructed using the least absolute shrinkage and selection operator regression. CT- and MR-based radiologic (R) and radiologic-radiomics (RR) models were developed by univariate and multivariate logistic regression. The performance of the RS/models was compared between two modalities. To investigate the added value of RS, the performance of the R models was compared with the RR models in HCC of all sizes and 2-5 cm in size.

STATISTICAL TESTS

Model performance was quantified by the area under the receiver operating characteristic curve (AUC) and compared using the Delong test.

RESULTS

Histopathologic MVI was identified in 161 patients (training set:validation set = 130:31). MRI-based RS/models tended to have a marginally higher AUC than CT-based RS/models (AUCs of CT vs. MRI, P: RS, 0.801 vs. 0.804, 0.96; R model, 0.809 vs. 0.832, 0.09; RR model, 0.835 vs. 0.872, 0.54). The improvement of RR models over R models in all sizes was not significant (P = 0.21 at CT and 0.09 at MRI), whereas the improvement in 2-5 cm was significant at MRI (P < 0.05) but not at CT (P = 0.16).

DATA CONCLUSION

CT and MRI had a comparable predictive performance for MVI in solitary HCC. The RS of MRI only had significant added value for predicting MVI in HCC of 2-5 cm.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Radiomics Analysis on Multiphase Contrast-Enhanced CT: A Survival Prediction Tool in Patients With Hepatocellular Carcinoma Undergoing Transarterial Chemoembolization

Patients with HCC receiving TACE have various clinical outcomes. Several prognostic models have been proposed to predict clinical outcomes for patients with hepatocellular carcinomas (HCC) undergoing transarterial chemoembolization (TACE), but establishing an accurate prognostic model remains necessary. We aimed to develop a radiomics signature from pretreatment CT to establish a combined radiomics-clinic (CRC) model to predict survival for these patients. We compared this CRC model to the existing prognostic models in predicting patient survival. This retrospective study included multicenter data from 162 treatment-naïve patients with unresectable HCC undergoing TACE as an initial treatment from January 2007 and March 2017. We randomly allocated patients to a training cohort (n = 108) and a testing cohort (n = 54). Radiomics features were extracted from intra- and peritumoral regions on both the arterial phase and portal venous phase CT images. A radiomics signature (Rad-signature) for survival was constructed using the least absolute shrinkage and selection operator method in the training cohort. We used univariate and multivariate Cox regressions to identify associations between the Rad- signature and clinical factors of survival. From these, a CRC model was developed, validated, and further compared with previously published prognostic models including four-and-seven criteria, six-and-twelve score, hepatoma arterial-embolization prognostic scores, and albumin-bilirubin grade. The CRC model incorporated two variables: The Rad-signature (composed of features extracted from intra- and peritumoral regions on the arterial phase and portal venous phase) and tumor number. The CRC model performed better than the other seven well-recognized prognostic models, with concordance indices of 0.73 [95% confidence interval (CI) 0.68–0.79] and 0.70 [95% CI 0.62–0.82] in the training and testing cohorts, respectively. Among the seven models tested, the six-and-12 score and four-and-seven criteria performed better than the other models, with C-indices of 0.64 [95% CI 0.58–0.70] and 0.65 [95% CI 0.55–0.75] in the testing cohort, respectively. The CT radiomics signature represents an independent biomarker of survival in patients with HCC undergoing TACE, and the CRC model displayed improved predictive performance.

Penumbra-based radiomics signature as prognostic biomarkers for thrombolysis of acute ischemic stroke patients: a multicenter cohort study

BACKGROUND AND PURPOSE

This study aimed at developing a radiomics signature (R score) as prognostic biomarkers based on penumbra quantification and to validate the radiomics nomogram to predict the clinical outcomes for thrombolysis for acute ischemic stroke (AIS) patients.

METHODS

In total, 168 patients collected from seven centers were retrospectively included. A score of mismatch was defined as MIS. Based on a short-term clinical label, 456 radiomics features were evaluated with feature selection methods. R score was constructed with the selected features. To compare the predictive capabilities of the clinical factors, MIS, and R score, three nomograms were developed and evaluated, according to the short-term clinical assessment on day 7. Finally, the radiomics nomogram was validated by predicting the 3-month clinical outcomes of AIS patients, in an external cohort.

RESULTS

R scores were found to be significantly higher in patients with favorable clinical outcomes in both training and validation datasets. The predictive value of the radiomics nomogram estimating favorable clinical outcomes was modest, with a concordance index (C-index) of 0.695 [95% confidence interval (CI) 0.667-0.723) in an external validation dataset. In addition, the area under curve (AUC) of the radiomics nomogram predicting favorable clinical outcome reached 0.886 (95% CI 0.809-0.963) on day 7 and 0.777 (95% CI 0.666-0.888) at 3 months.

CONCLUSIONS

The radiomics signature is an independent biomarker for estimating the clinical outcomes in AIS patients. By improving the individualized prediction of the clinical outcome for AIS patients 3 months after onset, the radiomics nomogram adds more value to the current clinical decision-making process.

Altered amplitude of low-frequency fluctuation in basal ganglia correlates to pulmonary ventilation function in COPD patients: A resting-state fMRI study

INTRODUCTION

Patients under chronic obstructive pulmonary disease (COPD) has been reported to be associated with a higher prevalence of cognitive impairment (CI). However, it is still largely unknown whether the aberrant resting-state spontaneous neuronal activity pattern reflected by the amplitude of low-frequency fluctuation (ALFF) analysis will be associated with the CI in COPD patients.

MATERIALS

A total of 28 COPD patients and 26 healthy controls were enrolled in this study. Of all the subjects, structural and functional MRI data, spirometry tests performance and neuropsychological assessments of different cognitive domains were collected. Voxel-based two-sample t tests were used to detect brain regions showing differences in the ALFF value between COPD patients and healthy controls. An additional fMRI runs with supplementary oxygen delivery were employed to explore the impact of elevated partial pressure of oxygen (PaO₂ ) or moderate hyperoxia on ALFF in COPD patients and healthy controls respectively.

RESULTS

More extensive white matter lesion was detected in COPD patients. COPD patients exhibit decreased ALFF value in bilateral basal ganglia areas and right thalamus, and aberrant ALFF value is correlated with PaO₂ and pulmonary ventilation function (FEV1%pred). COPD patients performed worse in the Digit Span Test (reverse), Digit Symbol Substitution Test, Trail-making test (A and B) than controls. After supplementary oxygen inhalation, the ALFF value of basal ganglia and right thalamus significantly increased in the controls, but not in the COPD patients.

CONCLUSIONS

COPD patients mainly exhibit impaired executive function but not long-term memory in cognitive function assessment. Aberrant ALFF alteration in the deep brain may be directly related to lower PaO₂ in COPD patients.

Structural change of thalamus in cirrhotic patients with or without minimal hepatic encephalopathy and the relationship between thalamus volume and clinical indexes related to cirrhosis

Aberrant brain structural change in cirrhotic patients with or without hepatic encephalopathy is one of the most typical cases in voxel-based morphometry (VBM) studies. However, there exist inconsistent results regarding to the volume change of the thalamus. Furthermore, the relationship between thalamus structural change and cirrhotic symptoms has not yet been fully elucidated. To address these two issues, we repeated two VBM analyses in SPM and FreeSurfer and compared the two measurements with manually measured thalamic volumes. We also correlated the VBM results with clinical indexes related to cirrhosis to further investigate the relationship between thalamic structural change and liver cirrhosis. The inconsistent result of thalamic structural change was successfully reproduced in regard to the volume measurements of SPM and FreeSurfer. The manually measured results demonstrate an increase in the volume of the thalamus in cirrhotic patients compared to healthy controls, which differs from the results of FreeSurfer. The structural change of thalamus closely correlated with the blood biochemical indexes, including albumin levels, blood coagulation time, and AST/ALT ratio. All of these biochemical indexes are closely related to the severity of liver cirrhosis. Beyond all the results, this study also provides a good demonstration of the difference between multiple VBM measurements for clinicians.

Cloning and analysis of a novel cDNA from Trichinella spiralis encoding a protein with an FYVE zinc finger domain

A cDNA library from Trichinella spiralis adults 3 days post-infection was screened with a cDNA probe, designated T 54, derived from a newborn larvae subtracted cDNA library. Sequence analysis showed that the positive clone contained a cDNA insert of 1464 bp in length with a single open reading frame of 1290 bp, which encoded a protein of 429 amino acids with a putative molecular mass of 49.9 k Da. Database analysis predicted the deduced protein had a leucine zipper motif and an FYVE zinc finger domain. The recombinant fusion protein was expressed and rabbit anti-recombinant protein sera reacted with a single peptide migrating at approximately 55 k Da in crude worm extract from muscle larvae, adults and newborn larvae stages.

Molecular cloning of a cDNA encoding a putative cuticle collagen of Trichinella spiralis

A 5-day-old adult stage-specific cDNA fragment from Trichinella spiralis was identified by suppression subtractive hybridization and was used as a probe to screen the cDNA library. The cDNA sequence coding for a putative T. spiralis cuticle collagen was isolated. The cDNA encoded an open reading frame of 343 amino acid residues with molecular weight of 35.1 k Da. The deduced protein contained an N-terminal signal peptide, a nematode cuticle collagen N-terminal domain and a collagen triple helix repeat domain. Searches in GenBank using BLASTP showed up to 47% identity to cuticle collagens from other nematodes. Southern blot analysis of genomic DNA indicated this gene was present as a single copy in T. spiralis genome.

Involvement of Sp1 in the transcriptional regulation of the rat insulin-like growth factor-1 gene

Most insulin-like growth factor-I (IGF-I) transcripts are initiated in exon 1, but mechanisms of regulation are not well understood. Since potential Sp1 sites are found in footprinted regions within approximately 360 bp upstream and downstream from the major initiation sites in exon 1, we explored the involvement of Sp1 and Sp3 in regulation of IGF-1 expression. Gel shift assays showed strong Sp1 binding to the downstream site, but binding to the upstream site was weak; Sp1 bound to a CCTGCCCA sequence in downstream footprint region V, and Sp3 binding was centered on the same sequence. IGF-I basal promoter constructs containing a mutation in the downstream Sp1 site exhibited a 32% decrease in expression in CHO cells and a 75% decrease in HepG2 cells, indicating the importance of Sp1 for expression in vivo. Sp1 and Sp3 expression vectors provided three- to five-fold stimulation of wild-type IGF-I constructs, but had little effect on a construct containing a mutation in the downstream Sp1 site, and Sp1 had comparable effects in Drosophila SL2 cells. IGF-I heterologous promoter constructs exhibited similar responses: in both SL2 cells and CHO cells, stimulation by Sp1 was enhanced with constructs containing downstream region V. Since Sp1 also stimulated expression of concatamers of putative cis-acting sites fused to the SV40 promoter enhancer in pGL3, the results in combination indicate that the presence of IGF-I region V is sufficient to permit stimulation by Sp1.

CONCLUSION

Sp1 and related factors may play an important role in the regulation of IGF-I gene transcription, through interactions with region V downstream from the major initiation sites in exon 1.

Vascular expression of extracellular superoxide dismutase in atherosclerosis

We characterized a novel form of extracellular superoxide dismutase (ecSOD) in atherosclerotic vessels. Specific activity and protein expression of ecSOD was increased two- to threefold in apo E-deficient compared with control aortas. RNase protection assays demonstrated that the expected ecSOD transcript was not increased in either apo E-deficient mice or cholesterol-fed LDL receptor-deficient mice, but that a second, lower molecular weight transcript was present and became predominant as atherosclerosis progressed. Sequence analysis revealed that this novel ecSOD has a 10-bp deletion in the 3' untranslated region and an asparagine to aspartic acid mutation at amino acid 21. Studies of isolated macrophages and immunohistochemistry suggested that the truncated ecSOD transcript was expressed by lipid-laden but not control macrophages. Recombinant wild-type and novel ecSODs expressed in Sf9 cells exhibited similar SOD activities. These experiments show that ecSOD expression is increased in atherosclerotic vessels and that this is characterized by an alteration in mRNA and protein structure. Further, the source of this altered ecSOD is likely the lipid-laden macrophage. The enzymatic properties of this novel ecSOD may have important implications for the function of the lipid-laden macrophage and the atherosclerotic process.

Reactive oxygen species produced by macrophage-derived foam cells regulate the activity of vascular matrix metalloproteinases in vitro. Implications for atherosclerotic plaque stability

Vulnerable areas of atherosclerotic plaques often contain lipid-laden macrophages and display matrix metalloproteinase activity. We hypothesized that reactive oxygen species released by macrophage-derived foam cells could trigger activation of latent proforms of metalloproteinases in the vascular interstitium. We showed that in vivo generated macrophage foam cells produce superoxide, nitric oxide, and hydrogen peroxide after isolation from hypercholesterolemic rabbits. Effects of these reactive oxygens and that of peroxynitrite, likely to result from simultaneous production of nitric oxide and superoxide, were tested in vitro using metalloproteinases secreted by cultured human vascular smooth muscle cells. Enzymes in culture media or affinity-purified (pro-MMP-2 and MMP-9) were examined by SDS-PAGE zymography, Western blotting, and enzymatic assays. Under the conditions used, incubation with xanthine/xanthine oxidase increased the amount of active gelatinases, while nitric oxide donors had no noticeable effect. Incubation with peroxynitrite resulted in nitration of MMP-2 and endowed it with collagenolytic activity. Hydrogen peroxide treatment showed a catalase-reversible biphasic effect (gelatinase activation at concentrations of 4 microM, inhibition at > or = 10-50 microM). Thus, reactive oxygen species can modulate matrix degradation in areas of high oxidant stress and could therefore contribute to instability of atherosclerotic plaques.

Transcriptional regulation of the insulin-like growth factor-I receptor gene: evidence for protein kinase C-dependent and -independent pathways

An important mechanism whereby growth factors stimulate vascular smooth muscle cell proliferation is by increasing insulin-like growth factor (IGF)-I receptor binding. To characterize the mechanisms involved, we studied transcription of the IGF-I receptor gene in rat aortic smooth muscle cells. Angiotensin II (100 nM) and basic fibroblast growth factor (5 ng/ml) caused a marked increase in IGF-I receptor messenger RNA (mRNA) levels, peaking at 3 h (215 +/- 16.8% and 85 +/- 7.4% above control, respectively). Nuclear run-on assays indicated that angiotensin II and fibroblast growth factor stimulated IGF-I receptor gene transcription by 2.1- and 2.5-fold, respectively. Down-regulation of protein kinase C, a serine/threonine kinase that is important in growth factor-activated signal transduction, completely inhibited fibroblast growth factor- but not angiotensin II-mediated up-regulation of IGF-I receptor mRNA. The protein kinase C inhibitors chelerythrine (3 microns), calphostin C (100 nM), and staurosporine (10 nM) also blocked fibroblast growth factor but not angiotensin II induction of IGF-I receptor mRNA. Thus, angiotensin II and fibroblast growth factor transcriptionally regulate the IGF-I receptor gene by protein kinase C-independent and -dependent pathways, respectively. In view of our prior data indicating that IGF-I receptor density is a critical determinant of vascular smooth muscle cell growth, our findings have particular relevance to understanding mechanisms whereby growth factors regulate vascular proliferation in vivo.

Regulation of vascular smooth muscle cell insulin-like growth factor I receptors by phosphorothioate oligonucleotides. Effects on cell growth and evidence that sense targeting at the ATG site increases receptor expression

We have recently shown that insulin-like growth factor I (IGF I) is a mediator of angiotensin II-induced mitogenesis in vascular smooth muscle cells (Delafontaine, P., and Lou H. (1993) J. Biol. Chem. 268, 16866-16870). To study the role of the IGF I receptor in vascular smooth muscle cell growth, phosphorothioate oligonucleotides were used to modulate IGF I receptors. An antisense oligonucleotide targeting the ATG site inhibited basal and serum-induced DNA synthesis in vascular smooth muscle cells. Mismatch oligonucleotide had no effect, while surprisingly sense oligonucleotide increased IGF I receptor number and basal and serum-induced DNA synthesis. A 51% reduction in IGF I receptor number following exposure to 5 microM antisense oligonucleotide markedly inhibited angiotensin II-induced mitogenesis. A 70% increase in IGF I receptor number following exposure to 5 microM sense oligonucleotide resulted in a 4-fold increase in basal [3H]thymidine incorporation, and angiotensin II (1-1000 nM) had no additive stimulatory effect. An antisense oligonucleotide targeting a sequence starting at +109 base pairs (relative to ATG) also reduced IGF I receptor number, however, the corresponding sense oligonucleotide was without effect. These findings demonstrate that alterations in vascular smooth muscle cell IGF I receptor density play a critical role in the proliferative response of vascular smooth muscle cells to serum and to angiotensin II. In addition, the surprising observation that an ATG-directed sense oligonucleotide up-regulates IGF I receptors identifies a novel effect of oligonucleotides on gene expression.