Monocarboxylate transporters facilitate succinate uptake into brown adipocytes

Uptake of circulating succinate by brown adipose tissue (BAT) and beige fat elevates whole-body energy expenditure, counteracts obesity and antagonizes systemic tissue inflammation in mice. The plasma membrane transporters that facilitate succinate uptake in these adipocytes remain undefined. Here we elucidate a mechanism underlying succinate import into BAT via monocarboxylate transporters (MCTs). We show that succinate transport is strongly dependent on the proportion that is present in the monocarboxylate form. MCTs facilitate monocarboxylate succinate uptake, which is promoted by alkalinization of the cytosol driven by adrenoreceptor stimulation. In brown adipocytes, we show that MCT1 primarily facilitates succinate import. In male mice, we show that both acute pharmacological inhibition of MCT1 and congenital depletion of MCT1 decrease succinate uptake into BAT and consequent catabolism. In sum, we define a mechanism of succinate uptake in BAT that underlies its protective activity in mouse models of metabolic disease.

A genome-wide genomic score added to standard recommended stratification tools does not improve the identification of patients with very low bone mineral density

The role of integrating genomic scores (GSs) needs to be assessed. Adding a GS to recommended stratification tools does not improve the prediction of very low bone mineral density. However, we noticed that the GS performed equally or above individual risk factors in discrimination.

PURPOSE

We aimed to investigate whether adding a genomic score (GS) to recommended stratification tools improves the discrimination of participants with very low bone mineral density (BMD).

METHODS

BMD was measured in three thoracic vertebrae using CT. All participants provided information on standard osteoporosis risk factors. GSs and FRAX scores were calculated. Participants were grouped according to mean BMD into very low (<80 mg/cm3), low (80-120 mg/cm3), and normal (>120 mg/cm3) and according to the Bone Health and Osteoporosis Foundation recommendations for BMD testing into an "indication for BMD testing" and "no indication for BMD testing" group. Different models were assessed using the area under the receiver operating characteristics curves (AUC) and reclassification analyses.

RESULTS

In the total cohort (n=1421), the AUC for the GS was 0.57 (95% CI 0.52-0.61) corresponding to AUCs for osteoporosis risk factors. In participants without indication for BMD testing, the AUC was 0.60 (95% CI 0.52-0.69) above or equal to AUCs for osteoporosis risk factors. Adding the GS to a clinical risk factor (CRF) model resulted in AUCs not statistically significant from the CRF model. Using probability cutoff values of 6, 12, and 24%, we found no improved reclassification or risk discrimination using the CRF-GS model compared to the CRF model.

CONCLUSION

Our results suggest adding a GS to a CRF model does not improve prediction. However, we noticed that the GS performed equally or above individual risk factors in discrimination. Clinical risk factors combined showed superior discrimination to individual risk factors and the GS, underlining the value of combined CRFs in routine clinics as a stratification tool.

Lactate regulates cell cycle by remodelling the anaphase promoting complex

Lactate is abundant in rapidly dividing cells owing to the requirement for elevated glucose catabolism to support proliferation1-6. However, it is not known whether accumulated lactate affects the proliferative state. Here we use a systematic approach to determine lactate-dependent regulation of proteins across the human proteome. From these data, we identify a mechanism of cell cycle regulation whereby accumulated lactate remodels the anaphase promoting complex (APC/C). Remodelling of APC/C in this way is caused by direct inhibition of the SUMO protease SENP1 by lactate. We find that accumulated lactate binds and inhibits SENP1 by forming a complex with zinc in the SENP1 active site. SENP1 inhibition by lactate stabilizes SUMOylation of two residues on APC4, which drives UBE2C binding to APC/C. This direct regulation of APC/C by lactate stimulates timed degradation of cell cycle proteins, and efficient mitotic exit in proliferative human cells. This mechanism is initiated upon mitotic entry when lactate abundance reaches its apex. In this way, accumulation of lactate communicates the consequences of a nutrient-replete growth phase to stimulate timed opening of APC/C, cell division and proliferation. Conversely, persistent accumulation of lactate drives aberrant APC/C remodelling and can overcome anti-mitotic pharmacology via mitotic slippage. In sum, we define a biochemical mechanism through which lactate directly regulates protein function to control the cell cycle and proliferation.

Monocarboxylate transporters facilitate succinate uptake into brown adipocytes

Uptake of circulating succinate by brown adipose tissue (BAT) and beige fat elevates whole body energy expenditure, counteracts obesity, and antagonizes systemic tissue inflammation in mice. The plasma membrane transporters that facilitate succinate uptake in these adipocytes remain undefined. Here we elucidate a mechanism underlying succinate import into BAT via monocarboxylate transporters (MCTs). We show that succinate transport is strongly dependent on the proportion of it present in the monocarboxylate form. MCTs facilitate monocarboxylate succinate uptake, which is promoted by alkalinization of the cytosol driven by adrenoreceptor stimulation. In brown adipocytes, we show that MCT1 primarily facilitates succinate import, however other members of the MCT family can partially compensate and fulfill this role in the absence of MCT1. In mice, we show that acute pharmacological inhibition of MCT1 and 2 decreases succinate uptake into BAT. Conversely, congenital genetic depletion of MCT1 alone has little effect on BAT succinate uptake, indicative of additional transport mechanisms with high capacity in vivo . In sum, we define a mechanism of succinate uptake in BAT that underlies its protective activity in mouse models of metabolic disease.

Diagnostic performance of on-site computation of quantitative flow ratio by a coronary computed tomography angiography based algorithm: comparison of distal and lesion-specific measurements

Introduction

Guidelines recommend secondary ischemia assessment following a coronary computed tomography angiography (CTA) with suspected obstructive coronary artery disease (CAD). Coronary CTA-derived quantitative flow ratio (CT-QFR) is an on-site technique performed on acquired CTA images that estimates the functional severity of a coronary stenosis. However, CT-QFR measurements are available throughout the coronary vessel with no clear recommendations as to which specific values should be used for identifying obstructive CAD, e.g. most distal or lesion-specific values.

Purpose

First, to investigate the feasibility of CT-QFR and the correlation and agreement with invasive fractional flow reserve (FFR). Secondly, to compare the diagnostic performance of distal versus lesion-specific CT-QFR for identifying obstructive CAD defined by invasive coronary angiography (ICA) with FFR.

Methods

A total of 1732 prospectively included patients with symptoms suggestive of CAD referred for CTA were included. All patients with ≥50% diameter stenosis (DS) on CTA were subsequently referred for ICA with conditional FFR in lesions with 30–89%DS. Obstructive CAD was defined by ICA as FFR ≤0.80 or high-grade stenosis by visual assessment (≥90%DS). A blinded analysis of CT-QFR was performed in patients referred to ICA with measurements at the distal end of a vessel (distal CT-QFR) and 1 cm distal to stenotic lesions on CTA (lesion-specific). CT-QFR ≤0.80 was defined as abnormal. For correlation analyses to invasive FFR, CT-QFR was assessed corresponding to the position of the invasive pressure sensor.

Results

In total, 445/1732 (25%) patients had suspected obstructive CAD at CTA and underwent subsequent ICA. CT-QFR analysis was feasible in 423/445 (95%) patients. CT-QFR correlated (Pearson's rho 0.54, p&lt;0.001) and agreed (mean difference –0.02±0.09) to FFR with CT-QFR overestimating FFR (Fig. 1). Obstructive CAD was identified in 190/423 (44%) patients by ICA. Distal and lesion-specific CT-QFR classified 196 (46%) and 171 (40%) patients as abnormal, respectively. Areas under the receiver-operating characteristic curves for distal versus lesion-specific CT-QFR were similar (0.86 (95% CI: 0.82–0.89) vs. 0.86 (0.82–0.90), p=0.80). Sensitivities for distal and lesion-specific CT-QFR were 78% (95% CI: 71–84) vs. 74% (67–80), p=0.01, respectively, and specificities 79% (95% CI: 74–84) vs. 87% (82–91), p&lt;0.01, respectively. Distal and lesion-specific CT-QFR had similar diagnostic accuracy (79 (95% CI: 75–83), vs. 81 (77–85), p=0.07) (Fig. 2).

Conclusion

In patients with suspected obstructive CAD on CTA, non-invasive estimation of FFR using CT-QFR is feasible with moderate correlation and good agreement with invasive FFR. Overall diagnostic performance of distal and lesion-specific values for discriminating obstructive CAD by invasive FFR are similar. The use of CT-QFR could therefore potentially reduce the need for referral to invasive angiography after CTA.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Aarhus UniversityRegion Mid Jutland

Prognostic impact of coronary artery calcifications in patients with newly diagnosed prostate cancer

Background

Patients diagnosed with prostate cancer (PCa) are known to be at increased risk of cardiovascular events. Because of the ageing population and better cancer treatment, the number of these patients is increasing. A prostate-specific membrane antigen positron emission tomography (PSMA-PET) is guideline recommended as part of the diagnostic workup. This scan includes a non-ECG-gated computed tomography (CT) of the thorax, allowing assessment of coronary artery calcifications (CAC). It is not well-established, whether estimation of CAC based on this CT scan can identify patients with increased risk of major adverse cardiac events (MACE) and thus possibly improve therapy and prognosis.

Purpose

This study aims to assess CAC and evaluate whether high calcium scores predict the risk of MACE in patients newly diagnosed with PCa.

Methods

We identified 634 consecutive patients diagnosed with PCa and undergoing PSMA-PET from 2016 to 2019 in an area of 300.000 residents. In total, 63 patients were excluded due to prior revascularization. The remaining 571 patients (mean age 69.9±6.7 years) were included. Patients were followed until June 2021 or until an event occurred (mean follow-up 962±372 days). We used a standard cardiac CT software to assess CAC. Information on MACE defined as all-cause mortality, stroke and myocardial infarction were obtained from electronic patient files. We divided patients into five groups based on their coronary artery calcium score (CACS): 0–10, 11–99, 100–399, 400–999, and + 1000. Cox regression analysis was used to compute the hazard ratios (HR) for MACE with CACS 0–10 as reference while adjusting for age, hypertension diabetes, and treatment with aspirin and statins.

Results

We found a significantly increasing risk of MACE with increasing CACS after adjustment for risk factors. For CACS 100–399 (n=136): HR 2.10 (95% CI: 0.98–4.51, p=0.056), for CACS 400–999 (n=79): HR of 2.99 (95% CI: 1.35–6.59, p=0.007) and for CACS +1000 (n=150): HR 3.06 (95% CI: 1.37–6.85, p=0.006) (Figure 1). Cardiovascular disease prevention treatment with statins and aspirin was 53% and 16% in patients with CACS 400–999 and 52% and 19% in patients with CACS + 1000.

Conclusion

In patients with PCa, estimating coronary calcium score based on non-ECG-gated CT scans, which are performed as part of the diagnostic workup, predicts the occurrence of MACE. In the patient group with the highest CAC, a four-year event rate of 24% was found. In combination with the finding of infrequent use of statin and aspirin, this emphasizes the possibility of early detection of high CAC in patients with PCa and illustrates the potential for more extensive use of preventive treatment. Future studies should investigate the effect of preventive treatment being initiated in patients with PCa and high CAC.

Funding Acknowledgement

Type of funding sources: None.

Comparison of second-line on-site computed quantitative flow ratio from coronary computed tomography angiography to PET perfusion imaging for detecting obstructive coronary artery disease

Introduction

In patients with suspected obstructive coronary artery disease (CAD) on coronary computed tomography (CTA), guidelines endorse second-line selective testing for hemodynamic evaluation of suspected CAD. A variety of non-invasive modalities are available, and myocardial perfusion imaging with Rubidium-82 positron emission tomography (PET) is an established method with high diagnostic performance. Recently, an on-site method estimating computed tomography-derived quantitative flow ratio (CT-QFR) showed promising results for discriminating obstructive CAD. However, no study has compared the diagnostic performances of PET and CT-QFR.

Purpose

To assess a possible non-inferiority of CT-QFR compared to PET in patients with suspected obstructive CAD at CTA using invasive coronary angiography (ICA) with fractional flow reserve (FFR) as reference.

Methods

Patients (n=1732, 57% males, age 59±9.5) referred on a clinical indication with symptoms suggestive of obstructive CAD underwent routine CTA. Patients with ≥50% diameter stenosis (DS) on CTA were referred for PET and subsequent ICA with FFR. CT-QFR was analyzed post-hoc blinded to PET and ICA results.

Abnormal CT-QFR was defined as CT-QFR ≤0.80 in any vessel with a diameter ≥1.5mm. An independent core-lab evaluated PET scans as abnormal/normal with optional analyst-dependent application of pre-specified criteria; summed stress score of ≥4 in ≥2 contiguous segments, vessel-specific myocardial blood flow (MBF) &lt;2.00 ml/g/min, global myocardial blood flow reserve ≤1.8, and/or transient ischemic dilatation ratio &gt;1.13. Obstructive CAD was defined as ICA with FFR ≤0.80 or high-grade stenosis (≥90% DS).

Results

In total, 445/1732 patients (25%) had suspected obstructive CAD on CTA of whom 400/445 patients (90%) underwent subsequent PET and ICA. CT-QFR was successfully analysed in 383/400 (96%) patients classifying 174/383 (45%) patients as having disease. In comparison, PET classified 130/383 (34%) patients as having disease. In total, obstructive CAD by ICA with FFR was identified in 162 (42%) patients.

There was no significant difference in area under the receiver-operating characteristic curves for CT-QFR compared to the best performing PET metric (lowest vessel-specific MBF); 0.84 (95% CI 0.80–0.89) vs. 0.81 (0.77–0.85), p=0.19)) (Fig. 1). Overall diagnostic accuracy of CT-QFR versus PET was similar (78% (95% CI 74–82) vs. 77% (72–81), p=0.70. Sensitivities for CT-QFR and PET were 78% (71–84) and 63% (55–70), p&lt;0.01, respectively, and specificities 78% (72–84) and 87% (82–91), p=0.01, respectively (Fig. 2). Three-vessel or left main disease on ICA was correctly identified in 30/31 patients by both CT-QFR and PET.

Conclusion

In patients with suspected obstructive CAD by CTA, second-line CT-QFR was non-inferior to PET for discriminating obstructive CAD by invasive FFR; Although diagnostic accuracy was similar, CT-QFR demonstrated higher sensitivity while PET showed higher specificity

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Aarhus University PhD fellowshipRegion Mid Health Research Foundation

An acoustic based risk score in addition to pre-test probability estimation for coronary artery disease improves risk classification in patients with suspected coronary artery disease

Background

The 2021 American College of Cardiology (ACC)/American Heart Association (AHA) Guideline for Evaluation and Diagnosis of Chest Pain introduced a new pre-test probability (PTP)-table for risk stratification of patients with symptoms suggestive of coronary artery disease (CAD). The CAD-score, an acoustic-based risk score for obstructive CAD, has previously shown good rule out capability in patients with suggested CAD when added to PTP.

Purpose

To investigate the potential of the acoustic CAD-score to 1) reclassify patients from intermediate-high to low PTP, and 2) improve risk-stratification in patients with low PTP, when added to the 2021 AHA/ACC PTP.

Methods

This is a retrospective study of patients with successfully obtained CAD-score from The Danish study of Non-Invasive testing in Coronary artery Disease 1 (Dan-NICAD 1) of patients without known CAD referred for coronary computed tomography angiography with angina pectoris. Patients with suspected obstructive CAD underwent invasive angiography. CAD-score was obtained with a non-invasive acoustic device analysing heart sounds based on CAD-related turbulence. CAD-score≤20 indicated low probability of CAD. PTP was calculated from sex, age, and angina symptoms according to current AHA/ACC Guidelines. Low likelihood of CAD was defined as PTP≤15%, and intermediate-high likelihood as PTP&gt;15%. Hemodynamic obstructive CAD was defined as visual luminal diameter stenosis &gt;90% on angiography or FFR&lt;0.80%.

Results

Among the 1475 included patients (52.3% women, median age 57 years IQR [50–64[), 36.4% were categorized as low likelihood of CAD (PTP≤15%), and 9.8% of patients had obstructive CAD. Compared to patients with PTP≤15%, patients with PTP&gt;15%, were older, more often hypertensive (49.8% vs. 35.5%), had a higher median CAD-score (28 [22–38] vs. 16 [12–22]), and had more obstructive CAD (12.4% vs. 5.2%). CAD-score reclassified 17.6% of patients with intermediate-high likelihood to a low likelihood of CAD and decreased the post-test probability of obstructive CAD from 5.2% to 4.7%. Subgroup analyses showed reclassification was greater in men, patients with PTP ≤25%, age &lt;70 years or no hypertension. In the 432 patients with PTP&gt;15%, age&lt;70 and no hypertension, 35.4% were reclassified to low likelihood, whereas only 2.4% of patients with PTP&gt;15%, age≥70 years or hypertension were ruled out by CAD-score ≤20. In patients with low PTP≤15%, CAD-score≤20 risk-stratified 361 (67.2%) patients to very low and 176 (32.8%) to an intermediate-low likelihood of CAD, but the post-test probabilities of CAD in both subgroups were still below the cut-off of 15 (3.6% vs. 8.5%).

Conclusion

Adding an acoustic-based CAD-score to the AHA/ACC PTP could potentially reduce the need for further diagnostic testing by 17.6% in patients with intermediate-high likelihood of CAD and in subgroups a reduction of 35% can be achieved. Use of CAD-score in low-likelihood patients only moderately improves risk classification.

Funding Acknowledgement

Type of funding sources: None.

AB1337 EFFECT OF CONTRAST MEDIA IN BONE MINERAL DENSITY MEASUREMENTS AND THE POTENTIALS FOR OPPORTUNISTIC OSTEOPOROSIS SCREENING USING QUANTITATIVE COMPUTED TOMOGRAPHY – A SYSTEMATIC LITERATURE REVIEW

Background

Quantitative computer tomography (QCT) has emerged as a screening tool for opportunistic measurements of volumetric bone mineral density (vBMD) from clinical CT scans, enabling early diagnosis of osteoporosis. However, intravenous contrast media administered during clinical CT examinations, calibration methods as well as different scan phases may influence vBMD and must be considered.1 Calibration methods include synchronous and asynchronous CT phantoms as well as phantom-less internal calibration.

Objectives

To investigate the effect of intravenous contrast media on QCT-measured vBMD. Furthermore, to review the effects of different calibration methods and scan protocols on vBMD.

Methods

In this systematic literature review, two independent reviewers (AH and AC) conducted a blinded screening for articles involving human participants who had undergone a contrast and non-contrast CT scan to measure vBMD. A total of 1,981 studies, published between 01.01.2000 and 17.01.2021, were screened and 9 eligible studies were included. A meta-analysis was conducted and standard mean differences (SMD) with 95% confidence intervals (CI) were calculated and presented in a forest-plot. Quality of studies was rated by the preliminary ROBINS-E risk of bias tool.2

Results

In total, the 9 studies included 515 patients. On average the vBMD SMD changed 0.45 (95% CI: 0.24-0.67, P < .0001) from non-contrast to contrast-enhanced (CE) scans at the lumbar region (Figure 1). Phantom-based QCT had a SMD of 0.64 (95% CI: 0.33-0.94, P < .0001) and phantom-less QCT had a SMD of 0.20 (95% CI: -0.00-0.40, P = 0.05). Subgroup analyses showed a mean arterial phase vBMD SMD of 0.29 (95% CI: 0.12-0.45 P < .0008) and a venous phase vBMD of 0.56 (95% CI: 0.30-0.81, P < .0001). All studies were deemed to have moderate or serious risk of bias by the ROBINS-E tool.

Figure 1.

Meta-analysis of standardized mean difference in lumbar spine vBMD (mg/cm3) change from non-contrast enhanced (non-CE) CT scans and contrast enhanced (CE) CT scans.

Conclusion

QCT-measured vBMD is higher in CE scans in both phantom-based and phantom-less scans compared to non-contrast CT. Our meta-analysis suggest that contrast has a larger impact on vBMD in phantombased vs. phantom-less and in venous phase scans vs. arterial phase scans, underlining not only the time-dependency but also the dependency of the calibration method. Arterial phase CT scans using internal calibration may be preferred when measuring vBMD in a clinical setting without an adjusting conversion factor. However, if CE scans are to be used in opportunistic vBMD screening, development of a universal calibration- and protocol specific conversion factor is of importance.

References

[1]Engelke, K. et al. Clinical Use of Quantitative Computed Tomography-Based Advanced Techniques in the Management of Osteoporosis in Adults: the 2015 ISCD Official Positions-Part III. J Clin Densitom18, 393-407, doi:10.1016/j.jocd.2015.06.010 (2015).

[2]Preliminary risk of bias for exposures tool template [http://www.bristol.ac.uk/population-health-sciences/centres/cresyda/barr/riskofbias/robins-e/].

Disclosure of Interests

Anders Hjortdal: None declared, Andia Cheneymann: None declared, Josephine Therkildsen: None declared, Ellen-Margrethe Hauge Speakers bureau: Received fees for speaking and/or consulting from AbbVie, Sanofi, Sobi, MSD, UCB;, Grant/research support from: Recieved research funding to Aarhus University Hospital from Novo Nordic Foundation, Danish Rheumatism Association, Danish Regions Medicine Grants, Roche, Novartis; travel expenses from Celgene, MSD, Pfizer, Roche, Sobi., Simon Winther: None declared, Morten Böttcher Speakers bureau: Disclose advisory board participation for NOVO Nordisk, Astra-Zeneca, Boeringer Ingelheim, Bayer, Sanofi, Novartis and Acarix outside of submitted work

POS1151 OPPORTUNISTIC BONE MINERAL DENSITY SCREENING IN PATIENTS UNDERGOING CARDIAC CT SCANS: EFFECT OF USING IMAGES CONTAINING INTRAVENOUS CONTRAST

Background

Osteoporosis is under-diagnosed worldwide causing increased risk of fractures and death (1). Computed tomography (CT) scans performed on other indications such as coronary artery disease harbor the potential for automatic detection of low volumetric bone mineral density (vBMD) of the vertebrae using quantitative CT (QCT); hence allowing estimation of future fracture risk (2). CT is often performed with intravenous (iv) contrast administration. In 2015, the International Society of Clinical Densitometry stated: “There is insufficient evidence to judge the effect of contrast agents on a classification of low BMD” (3); this position remains. Thus, it is important to assess the effect of contrast enhancement in order to broaden the potential of vBMD screening using routine CT scans.

Objectives

We aimed to compare thoracic vBMD measurements from CT scans with and without iv contrast enhancement.

Methods

This cross-sectional multicenter sub-study is based on a larger clinical trial, Dan-NICAD-1, from which we randomly selected a cohort of 136 participants. First, a non-contrast scan was performed followed by a contrast-enhanced scan during which 60-90mL of iv contrast was administered (Iomeron, 350 mgI/mL). Mindways QCT Pro software was used to measure BMD values (mg/cm3) and the mean estimate was calculated for each participant (4). American College of Radiology quantitative CT cut-off values for lumbar spine were used to categorize patients into very low (<80mg/cm3), low (80-120mg/cm3), or normal BMD (>120mg/cm3).

Results

In 136 participants undergoing cardiac CT (Table 1), we found a different mean vBMD before vs. after contrast; 117.5 mg/cm3 [95%CI: 111.6–123.4] vs. 132.1 mg/cm3 [95%CI: 125.1–139.1], p<.0001. The absolute difference was 14.7mg/cm3 [95%CI: 12.3–17.0]; the relative difference, was 12.5% [95% CI: 10.5–14.5]. In total, 8/15 (53%) participants changed from very low BMD to low BMD after contrast administration, and 21 participants (21/63, 33%) changed from low to normal BMD (Figure 1). No participants changed from very low BMD to normal BMD.

Table 1.

Demographics by vBMD*

CharacteristicsAll (n=136)Very low BMD (n=15)Low BMD (n=63)Normal BMD (n=58)Gender M:F89:478:749:1432:26Age, yrs (range)57±9 (40-73)64±6 (48-72)59±8 (44-73)54±8 (40-72)Mean vBMD before contrast, mg/cm92.2±16.168.0±10.598.0±10.1151.5±21.9Mean vBMD after contrast, mg/cm95.2±16.068.6±10.5100.8±10.3159.6±31.6Risk factorsDiabetes mellitus**16079Smoking status**Never6541744Former181710Active5252423Bone dataDXA performed previously**7232Osteoporosis diagnosed previously**1010Family history of osteoporosis**22589Anti-osteoporotic medication**152310

* Classifications defined by American College of Radiology and grouped using the non-enhanced CT. Data: number of participants, (range) and mean with standard deviations.

** Self-reported

Figure 1.

Participants with change in BMD category after contrast administration Figure 1. vBMD measurements before and after contrast administration. 33/136 participants changed BMD category illustrated by the dotted lines (80 mg/cm3; 120 mg/cm3). Black lines: increase in vBMD after contrast (n=29); blue lines: decrease in vBMD after contrast (n=4).

Conclusion

Our data suggest a significant effect of contrast on clinical vBMD measurements; thus, this should be adjusted for before using contrast-enhanced cardiac CT for opportunistic vBMD screening. This urges further studies on the effect of scan protocols on the contrast-enhanced increase in BMD.

References

[1]M. S. Nanes et al., Seminars in nuclear medicine44, 439-450 (2014).

[2]J. Therkildsen et al., Radiology296, 499-508 (2020).

[3]K. Engelke et al., Journal of clinical densitometry18, 393-407 (2015).

[4]J. Therkildsen et al., Journal of Clinical Densitometry23, (2018).

Acknowledgements

The Danish Osteoporosis Foundation, The Danish Council for Independent Research (DFF–7025–00103), the Danish Heart foundation (15-R99-A5837–22920), the Hede Nielsen Foundation, Acarix A/S (unrestricted grant) and Mrs. Lily Benthine Lunds Foundation of 1.6. 1978 supported this project. The authors would like to thank all study participants and the clinical staff involved in this project.

Disclosure of Interests

Andia Cheneymann: None declared, Josephine Therkildsen: None declared, Simon Winther Grant/research support from: Disclosed an unrestricted grant from Acarix A/S., Louise Nissen: None declared, Jesper Thygesen: None declared, Bente Langdahl Consultant of: Worked as a consultant for Amgen, UCB, Gedeon-Richter, Eli Lilly and Gedeon., Grant/research support from: Received honorariums from Amgen, UCB, Eli Lilly, Gedeon-Richter and Astellas. Received financial grants from Amgen and the Novo Nordic Foundation., Ellen-Margrethe Hauge Consultant of: Received honorariums and/or consulting fees from AbbVie, Sanofi, Sobi, and SynACT Pharma., Grant/research support from: Research grants to Aarhus University Hospital from Danish Regions Medicine Grants, Danish Rheumatism Association, Roche, Novartis, and Novo Nordic Foundation., Morten Böttcher Consultant of: Advisory board participation for NOVO Nordisk, Astra-Zeneca, Pfizer, Boeringer Ingelheim, Bayer, Sanofi, Novartis and Acarix.

An adipose lncRAP2-Igf2bp2 complex enhances adipogenesis and energy expenditure by stabilizing target mRNAs

lncRAP2 is a conserved cytoplasmic lncRNA enriched in adipose tissue and required for adipogenesis. Using purification and in vivo interactome analyses, we show that lncRAP2 forms complexes with proteins that stabilize mRNAs and modulate translation, among them Igf2bp2. Surveying transcriptome-wide Igf2bp2 client mRNAs in white adipocytes reveals selective binding to mRNAs encoding adipogenic regulators and energy expenditure effectors, including adiponectin. These same target proteins are downregulated when either Igf2bp2 or lncRAP2 is downregulated, hindering adipocyte lipolysis. Proteomics and ribosome profiling show this occurs predominantly through mRNA accumulation, as lncRAP2-Igf2bp2 complex binding does not impact translation efficiency. Phenome-wide association studies reveal specific associations of genetic variants within both lncRAP2 and Igf2bp2 with body mass and type 2 diabetes, and both lncRAP2 and Igf2bp2 are suppressed in adipose depots of obese and diabetic individuals. Thus, the lncRAP2-Igf2bp2 complex potentiates adipose development and energy expenditure and is associated with susceptibility to obesity-linked diabetes.

External validation of prediction models for obstructive coronary artery disease in patients with suspected stable coronary artery disease

Background

Pre-test probability (PTP) is an important tool in the diagnostic work-up for obstructive coronary artery disease (CAD) but must be calibrated to the declining disease prevalence in patients referred to diagnostic testing.

Purpose

To externally validate the published basic and clinical PTP models in a contemporary angina cohort with low prevalence of CAD and to compare with the reference European Society of Cardiology 2019 PTP (ESC 2019 PTP).

Methods

The validation cohort consisted of 42.328 patients (54% women, age ≥30 years, no previous CAD) with symptoms of CAD referred for cardiac computed tomography angiography in the western region of Denmark from 2008–2017 (3.3 million inhabitants). Obstructive CAD was defined from either invasive angiography as stenosis &gt;50%, or when performed, from FFR &lt;0.8 in coronary arteries with diameters &gt;2 mm.

The basic prediction model included type of angina, sex, and age, and the clinical model added diabetes, family history of CAD, and dyslipidemia. The ESC 2019 PTP was calculated from age, sex, and angina symptoms. Discrimination, calibration, and negative predictive value (NPV) were measured for all three models.

Results

Obstructive CAD was present in 3718 (8.8%). In the ESC 2019 PTP model, the basic model, and the clinical model 19.5%, 48.5%, and 55.7% were classified as very low risk and only 1.6%, 3.7%, and 3.5% of these had obstructive CAD, respectively (figure 1). Discrimination was similar for the three models with AUC of 0.76 (95% CI 0.75–0.77), 0.74 [0.73–0.75], and 0.76 [0.75–0.76], for the ESC 2019 PTP, basic, and clinical model, respectively. At the clinically relevant very low predicted probability (≤5%) of CAD, the clinical and basic model were very well calibrated, whereas the ESC 2019 PTP model overestimated the CAD prevalence. NPV at cut-off ≤5% were 98.4% [98.1–98.7] for the ESC 2019 PTP model, 96.3% [96.1–96.6] for the basic model, and 96.5% [96.3–96.7] for the clinical model. At cut-off &lt;15%, NPVs were 96.1% [95.8–96.3] for the ESC 2019 PTP model, 94.5% [94.2–94.7] for the basic model, and 94.2% [94.0–94.5] for the clinical model.

Conclusion

In a population with a prevalence of 8.8% obstructive CAD, a clinical prediction model including diabetes, family history of CAD, and dyslipidemia in addition to the variables of the ESC 2019 PTP model ruled out 36.2% more patients than the ESC 2019 PTP model (23.592 vs. 8245 patients) while only overlooking 1.9% more cases of obstructive CAD when choosing a cut-off ≤5%. Use of this model is therefore potentially cost saving.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Diagnostic accuracy and reclassification potential of the acoustic CADScor algorithm in intermediate risk patients with suspected coronary artery disease

Background

Validation studies of the 2019 European Society of Cardiology pre-test probability model (ESC-PTP) for coronary artery disease (CAD) report that 35–40% of patients have intermediate pre-test risk (ESC-PTP 5-&lt;15%). A clear strategy for deferral or referral in this group has not been established. Stratification tools with a high negative predictive value (NPV) are especially wanted to improve pre-test risk estimates.

Acoustic detections of coronary stenosis are a new technology which could potentially be useful to supplement PTP stratification. One of the devices, the CADScor®System, has been shown to down-classify &gt;40% of patients to low risk without increasing CAD prevalence. However, the clinical utility of using the CADScor algorithm (version (V)3.1) has not be validated.

Purpose

1) To validate the diagnostic performance of the CADScor®System (V3.1), and 2) to study the reclassification potential of a clinical likelihood strategy by ESC-PTP estimation supplemented by a CAD-score.

Methods

In total, 1732 patients without known CAD but with symptoms suggestive hereof underwent coronary CTA as a first-line diagnostic test. Based on an interview prior to coronary CTA, the ESC-PTP model was applied and sound recordings were performed using the acoustic CADScor® System. Patients with a suspected &gt;50% diameter stenosis in any coronary segment at coronary CTA were referred to investigation with Invasive angiography (ICA) with measurement of Fractional flow reserve (FFR).

The ESC-PTP risk estimation was divided according to the recommended cut-offs of &lt;5%, 5-&lt;15% and &gt;15% PTP of obstructive CAD. Haemodynamically obstructive CAD was defined as: (1) FFR value &lt;0.80, (2) luminal diameter stenosis reduction &gt;90%, or (3) luminal diameter stenosis reduction ≥50% if FFR was indicated but not performed. A predefined cut-off value of 20 was used for CAD-score values to rule-out CAD.

Results

A suspected stenosis was found in 439 patients (26%) after coronary CTA. The follow up with ICA with FFR showed significant stenoses in 198 patients (12%).

In the entire cohort using the ≤20 CAD-score cutoff for CAD rule-out, sensitivity was 85.3% (95% CI 79.5–89.9%), specificity was 40.3% (95% CI 37.8–42.9%), the PPV was 5.9% (95% CI 13.8–18.3%)), and the NPV was 95.4% (95% CI 93.4–96.9%). Hence, the disease prevalence of obstructive CAD was 4.6% in the ruled-out patients.

Applying the ≤20 CAD-score cutoff for CAD rule-out in intermediate risk patients (ESC-PTP 5-&lt;15%) a total of 316 patients (48%) were down-classified to low risk with an obstructive CAD prevalence of 3.5%.

Conclusion

Having high NPV, the CADscor holds excellent rule-out power. Interestingly, the CADscor has reclassification properties in intermediate CAD risk patients where almost 50% can be deferred form further testing without increasing obstructive CAD risk. Thus, the CADscor can supplement clinical assessment to guide decisions on the need for further testing.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The study was supported by the Health Research Fund of Central Denmark Region, Aarhus University Research foundation and by an institutional research grant from Acarix A/S, Denmark. Patient flowReclassification potential

Impact of socioeconomic position on coronary artery disease burden in men and women with de-novo symptoms suggestive of chronic coronary syndrome

Background

Low socioeconomic position (SEP) is associated with shorter life expectancy and one of the main drivers is an increase in cardiovascular deaths. A higher prevalence of risk factors only partly explains the complex multifactorial pathogenesis. The aim of this study was to investigate the association between SEP and the development of coronary artery disease (CAD) assessed as calcium score (CACS) at coronary computed tomography angiography (CCTA) as well as stenosis at downstream invasive coronary angiography (ICA) in a population presenting with symptoms suggestive of chronic coronary syndrome (CCS). A secondary aim was to establish whether SEP affects men and women differently.

Methods

We included 50,561 patients (Mean age 57.35±11.50, 53.7% women) from the Western Denmark Heart Registry (WDHR) with no previous CAD undergoing CCTA from 2008–2019 for suspected CCS. ICA was conducted in patients where obstructive CAD was not excluded at CCTA. Outcome measures was level of CACS and haemodynamically significant stenosis at ICA defined as either fractional flow reserve &lt;0.80 or visually assed diameter stenosis of ≥50% stenosis. Odds Ratio of haemodynamically significant stenosis at ICA was calculated using multiple logistic regression and models adjusted for risk factors (smoking, medical treatment for hypertension, medical treatment for high cholesterol, diabetes and family history of CAD). Information on SEP was obtained from national registries. We included mean individual income at age 30–60 or until CCTA (quintiles); and length of education (&lt;10 years, 10–13 years or &gt;13 years). Information on risk factors was obtained from the WDHR registry.

Results

Mean number of risk factors are presented in each educational group in Figure 1. Median CACS for women with &lt;10 years of education is 2 [0–82] vs. 0 [0–15] for women with &gt;13 years of education (p&lt;0.001). For men &lt;10 years of education median CACS is 10 [0–143] vs. 8 [0–118] for men with &gt;13 years of education (p=0.05) (Figure 1). Mean number of risk factors are presented at each level of income in Figure 2. For women with low income median CACS was 6 [0–103] vs. 0 [0–3] for women with high income (p&lt;0.001). For men with low income median CACS is 8 [0–144] vs. 5 [0–105] for men with high income (p=0.002) (Figure 2). The odds ratio (OR) of a stenosis at downstream ICA was 1.47 (p=0.004) for women with &lt;10 years of education vs. &gt;13 years of education and 1.17 for men (p=0.122). OR of stenosis at ICA was 2.40 (p&lt;0.001) for women with low income (1 quintile) using high income (5 quintile) as reference and 1.12 for men (p=0.321).

Conclusion

In de-Novo patients referred for CAD rule-out both coronary calcium score and the prevalence of stenosis at ICA is strongly correlated to low income and short education. The correlation seems to be stronger in women compared to men and calls for further research into the mechanism behind low SEP and atherosclerosis.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Hospital Unit West Jutland Research foundation Figure 2

Prevalence and severity of coronary artery disease linked to prognosis in psoriasis and psoriatic arthritis patients: a multi-centre cohort study

OBJECTIVES

(i) To estimate the prevalence and severity of coronary artery disease and (ii) to assess the risk of cardiovascular events and mortality, in patients with psoriasis and psoriatic arthritis (PsA) in a large-scale cohort of patients referred to coronary computed tomography angiography (CTA).

METHODS

This was a cross-sectional study with follow-up of 46,022 patients based on data from a Danish national CTA registry. Exposure was defined as psoriasis or PsA. A group of patients without psoriasis, PsA or any other inflammatory disease was used as reference. Cross-sectional primary outcomes were a coronary artery calcium score (CACS) >0 and CACS ≥400, and secondary outcome was obstructive CAD. At follow-up, the primary outcome was a composite endpoint of cardiovascular events and all-cause mortality. All outcomes were adjusted for traditional cardiovascular risk factors.

RESULTS

We identified 1356 psoriasis and 370 PsA patients. The adjusted odds ratio (OR) for psoriasis patients for CACS >0, CACS ≥400 and obstructive CAD was 1.26 (1.10-1.46), 1.25 (1.04-1.50) and 1.14 (0.98-1.33), respectively. For PsA patients, OR for CACS >0 was 1.28 (1.00-1.64). We found a crude hazard ratio (HR) of 1.49 (1.21-1.85) and adjusted HR of 1.14 (0.92-1.41) for the primary outcome in psoriasis patients.

CONCLUSIONS

In this population, both psoriasis and PsA were associated with an increased prevalence of coronary calcification. Psoriasis patients also showed an increased prevalence of severe calcification. Psoriasis patients were at increased risk for cardiovascular events and death, however not after adjusting for the effect of other predictors.

Protective succinate-SUCNR1 metabolic stress signaling gone bad

The TCA cycle metabolite succinate functions as an intra- and extracellular signal of metabolic stress. Based on the phenotype of UCP-1-deficient mice, Mills et al. (2021) now report in Nature Metabolism that accumulation of extracellular succinate due to impaired elimination in thermogenic fat drives liver inflammation and fibrosis through the succinate receptor SUCNR1.

Combining minimal risk stratification and prediction of obstructive CAD – clinical utility of a dual pre-test probability model

Background

The recently updated pre-test probability (PTP) model for diagnosing chronic coronary syndrome suggested by the European Society of Cardiology (ESC) was designed to predict the presence of obstructive coronary artery disease (CAD). In addition to this model, identification of non-obstructive CAD and utilization of preventive interventions may also lower rates of death and non-fatal myocardial infarction. Opposite to the ESC PTP, the minimal risk tool (MRT) is a new model developed to identify individuals without CAD but symptoms suggestive of CAD. We explored a combined use of the 2 models to predict the absence or presence of obstructive CAD.

Methods

This was a sub-study of the Danish study of Non-Invasive testing in Coronary Artery Disease (Dan-NICAD) which included patients with low-intermediate PTP of CAD. Minimal risk was defined as having a coronary calcium score of 0, no evidence of coronary atherosclerosis at coronary computed tomography angiography, and no cardiovascular (CV) events defined as myocardial infarction, death or revascularization in the mean observation period of 3.1 [2.7–3.4] years. Obstructive CAD was defined as a fractional flow reserve &lt;0.80 in a major vessel during invasive coronary angiography (ICA) or a high-grade stenosis by visual assessment (&gt;90% lumen reduction).

The risk factors included in the MRT were age, sex, smoking history, diabetes mellitus, dyslipidaemia, family history of premature CAD, hypertension, symptoms related to stress, and high-density lipoprotein concentration. Based on a point-system ranging from 0–5, the MRT and the ESC PTP were combined (dual-PTP) (figure 1). A dual-PTP ≤1 indicated very low risk. Using both minimal risk and obstructive CAD as references, the dual PTP was compared to the MRT and the ESC PTP through tests of model discrimination.

Results

Of the 1544 eligible patients, 710 (46%) had normal coronary arteries and no CV events. Obstructive CAD was diagnosed in 152 (10%).

Equivalent to a dual-PTP &lt;1 point, 209 patients with ESC PTP&lt;5% and MRT&gt;50% or ESC PTP 5–15% and MRT &gt;75% were classified as very low risk. Of these patients, 84% were at true minimal risk (red area figure 1). Furthermore, only 6 patients would have been diagnosed with obstructive CAD at ICA, and 0 events would be missed. The dual-PTP was non-inferior to the MRT and the ESC PTP in identifying patients having minimal risk and obstructive CAD, respectively (minimal risk: c-statistics 0.74 (0.72–0.77) vs. 0.76 (0.73–0.78); obstructive CAD: c-statistics 0.66 (0.62–0.70) vs. (0.67 (0.63–0.72)). The dual-PTP was superior to the ESC PTP in discriminating patients at minimal risk (c-statistics 0.74 (0.72–0.77) vs. 0.69 (0.67–0.71).

Conclusions

Combining the ESC PTP and the MRT, the dual-PTP seems to enable accurate prediction of both patients with minimal risk and patients with obstructive CAD. Based on the dual-PTP, patients can safely be deferred from or referred for diagnostic testing

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Aarhus University, Health Research Fund of Central Denmark Region

Pyruvate kinase M2 represses thermogenic gene expression in brown adipocytes

Utilizing the thermogenic capacity of brown adipose tissue is a potential anti-obesity strategy; therefore, the mechanisms controlling expression of thermogenesis-related genes are of interest. Pyruvate kinase (PK) catalyzes the last step of glycolysis and exists as four isoenzymes: PK, liver, PK, red blood cell, PK, muscle (PKM1 and PKM2). PKM2 has both glycolytic and nuclear functions. Here, we report that PKM2 is enriched in brown adipose compared with white adipose tissue. Specific knockdown of PKM2 in mature brown adipocytes demonstrates that silencing of PKM2 does not lead to a decrease in PK activity, but causes a robust upregulation of thermogenic uncoupling protein 1 (Ucp1) and fibroblast growth factor 21 (Fgf21) gene expression. This increase is not mediated by any of the known mechanisms for PKM2-regulated gene expression, thus implying the existence of a novel mechanism for PKM2-dependent effects on gene expression.

P870A genetic risk score is associated with increased coronary plaque burden but not specific plaque features: a coronary computed tomography study

Background

Genetic risk scores (GRSs) based on risk variants identified from genome-wide association studies (GWASs) predict coronary artery disease (CAD) risk. However, it is unknown whether the GRS is associated with coronary plaque burden or specific high-risk plaque features responsible for the clinical disease onset.

Purpose

To investigate if a GRS is associated with coronary plaque burden and specific plaque characteristics, in patients with suspected stable CAD referred for coronary computed tomography angiography (CTA).

Methods

We consecutively included and genotyped 1645 patients undergoing coronary CTA. Using LDPred, a previously validated GRS was calculated as the weighted sum of the number of CAD risk variants identified from the CARDIoGRAMplusC4D GWAS meta-analysis. Plaques were evaluated using an 18-segment model and characterized by stenosis severity (0%, 1–49%, 50–69%, 70–100%) and composition (calcified (>80% calcified), mixed-calcified (50–80% calcified), mixed-soft (20–50% calcified), or soft (<20% calcified)). The segment stenosis score and the coronary artery calcium score (CACS) were used as measures of plaque burden. Multivariate regression models were used to assess the effect per standard deviation (SD) of the GRS with adjustment for age, sex, hypertension, hypercholesterolemia, BMI, chest pain symptoms, and active smoking.

Results

For each SD increase in the GRS, the segment stenosis score increased with 49% (p=8.6e-27) and CACS increased with 110% (p=2.3e-24). The GRS was associated with a higher risk of plaque stenosis >50% (OR: 1.74, p=3.2e-15), calcified (OR: 1.65, p=3.0e-16), mixed-calcified (OR: 1.64, p=1.5e-8), mixed-soft (OR: 1.44, p=1.6e-6), and soft plaques (OR: 1.40, p=3.0e-6), and all coronary vessels were more often affected with plaques (all p-values <1.0e-4).

When analyzing the plaque characteristics (3007 plaques in 849 patients), the GRS was associated with stenosis severity (OR per severity category: 1.15 (p=0.005), but not with extent of calcification, proximal location, or presence in any of the major coronary vessels (all p-values >0.05).

GRS and Plaque burden

Conclusion

The GRS was strongly associated with the extent and severity of CAD at coronary CTA, but not any specific plaque characteristics per se. The results may suggest that polygenic risk based on large CAD-GWAS increases CAD risk through increased coronary plaque burden rather than specific plaque features.

P2713A genetic risk score improves discrimination of hemodynamically obstructive coronary artery disease (CAD) beyond the CAD Consortium scores in patients at low-to-intermediate risk of CAD

Background

Genetic risk scores (GRSs), based on variants identified in genome-wide association studies (GWAS), have been shown to predict risk of coronary artery disease (CAD). However, the clinical potential remains unknown.

Purpose

To investigate whether a GRS improves discrimination of hemodynamically obstructive CAD beyond the CAD Consortium scores and coronary artery calcium score (CACS) in patients referred for coronary computed tomography angiography (CTA).

Methods

We consecutively included and genotyped 1645 patients undergoing CACS scoring and coronary CTA on a suspicion of CAD. Using LDPred, a recently validated GRS was calculated as the weighted sum of the number of CAD risk variants identified from the CARDIoGRAMplusC4D GWAS meta-analysis. Patients with a ≥50% stenosis on CTA further underwent invasive coronary angiography (ICA) with fractional flow reserve (FFR). Hemodynamically obstructive CAD was defined as a visual ICA stenosis >90%, FFR <0.80, or a quantitative coronary analysis stenosis >50% if FFR was not feasible. Discrimination was evaluated by receiver-operating characteristics.

Results

Median age was 57 (interquartile range 50–64) years and 799 (49%) were males. Hemodynamically obstructive CAD was present in 14 (4%) with a low GRS (<20th percentile), 91 (9%) with an intermediate GRS (20th–80th percentile) and 53 (16%) with a high GRS (>80th percentile) (p<0.0001). Adding the GRS improved the area under the receiver-operating curve (AUC) on top of the CAD Consortium basic score (from 0.67 to 0.72, p=0.0052), and the CAD Consortium clinical score (0.70 to 0.74, p=0.0084), but not on top of the CAD Consortium clinical score + CACS (0.85 to 0.86, p=0.30). Improvement in discrimination on top of the CAD Consortium scores was predominantly driven by females ≤57 years (CAD Consortium basic score ± GRS: 0.60 to 0.78, p=0.0004; CAD Consortium clinical score ± GRS: 0.63 to 0.78, p=0.0007). The GRS did not improve discrimination in any subgroups including CACS (CAD Consortium clinical score + CACS ± GRS: all p-values >0.05).

Conclusion

A GRS improves discrimination of hemodynamically obstructive CAD beyond CAD consortium scores, particularly in young women. However, the additive discriminative value is attenuated in models including CACS.

P3624Prevalence and severity of coronary artery disease linked to prognosis in psoriasis patients referred for coronary computed tomography angiography: A multicentre cohort study

Background

Psoriasis (Pso) is a disease characterized by systemic inflammation and is associated with an increased risk of cardiovascular disease. However, the degree of coronary artery calcification in Pso and its relation to prognosis is largely unknown.

Purpose

The aim of this study was 1) to estimate the prevalence and severity of coronary artery disease (CAD) in this patient group and 2) to asses the risk of major adverse cardiovascular events (MACE) including revascularization and all-cause mortality after initial diagnosis and treatment in a large-scale cohort of patients who underwent coronary computed tomography angiography (CCTA) due to angina symptoms.

Methods

This study consists of two parts using data from the Western Denmark Heart Registry; a cross-sectional study included 40,125 patients and a follow-up study included 42,861 patients. Pso patients were identified by the National Patient Registry and verified by nationwide prescription and treatment code registers. Primary outcome in the cross-sectional study was a coronary artery calcium score (CACS) >0, with a secondary outcome defined as a CACS ≥400. In the follow-up study, the primary outcome was a combined outcome including myocardial infarction, revascularization, ischemic or unspecified stroke and all-cause mortality. Events within the first 90 days after CCTA were attributed to initial treatment and consequently excluded. All outcomes were adjusted for common cardiovascular risk factors and comorbidities.

Results

In the cross-sectional study 1,407 (3.5%) Pso patients were identified. OR was 1.31 (95% CI; 1.15–1.49) for CACS >0 and 1.33 (95% CI; 1.10–1.62) for CACS ≥400 in Pso patients compared to non-Pso patients. In the follow-up study 1,591 (3.7%) Pso patients were identified. The mean duration of follow-up after CCTA was 4.0 years (min/max 0.0/10.2). Crude HR for the combined outcome was 1.52 (95% CI; 1.24–1.87), while adjusted HR was 1.16 (95% CI; 0.95–1.43).

Conclusion

In this clinically relevant cohort of patients referred to CCTA for CAD rule out, coronary artery calcification was more frequent and more severe in Pso patients even compared to the control patients with several risk factors and angina symptoms, but without inflammatory diseases. An increased risk of the combined outcome of MACE including revascularization and all-cause mortality after initial treatment in Pso patients was found in the crude analysis. The increased risk seemed predominantly carried by an increase in traditional risk factors.

Coronary artery disease risk reclassification by a new acoustic-based score

To determine the potential of a non-invasive acoustic device (CADScor®System) to reclassify patients with intermediate pre-test probability (PTP) and clinically suspected stable coronary artery disease (CAD) into a low probability group thereby ruling out significant CAD. Audio recordings and clinical data from three studies were collected in a single database. In all studies, patients with a coronary CT angiography indicating CAD were referred to coronary angiography. Audio recordings of heart sounds were processed to construct a CAD-score. PTP was calculated using the updated Diamond-Forrester score and patients were classified according to the current ESC guidelines for stable CAD: low < 15%, intermediate 15–85% and high > 85% PTP. Intermediate PTP patients were re-classified to low probability if the CAD-score was ≤ 20. Of 2245 patients, 212 (9.4%) had significant CAD confirmed by coronary angiography ( ≥ 50% diameter stenosis). The average CAD-score was higher in patients with significant CAD (38.4 ± 13.9) compared to the remaining patients (25.1 ± 13.8; p < 0.001). The reclassification increased the proportion of low PTP patients from 13.6% to 41.8%, reducing the proportion of intermediate PTP patients from 83.4% to 55.2%. Before reclassification 7 (3.1%) low PTP patients had CAD, whereas post-reclassification this number increased to 28 (4.0%) (p = 0.52). The net reclassification index was 0.209. Utilization of a low-cost acoustic device in patients with intermediate PTP could potentially reduce the number of patients referred for further testing, without a significant increase in the false negative rate, and thus improve the cost-effectiveness for patients with suspected stable CAD.

Influence of Cardiac CT based disease severity and clinical symptoms on the diagnostic performance of myocardial perfusion

We aimed to identify factors influencing the sensitivity of perfusion imaging after an initial positive coronary computed tomography angiography (CCTA) using invasive coronary angiography (ICA) with conditional fractional flow reserve (FFR) as reference. Secondly we aimed to identify factors associated with revascularisation and to evaluate treatment outcome after ICA. We analysed 292 consecutive patients with suspected significant coronary artery disease (CAD) at CCTA, who underwent perfusion imaging with either cardiac magnetic resonance (CMR) or myocardial perfusion scintigraphy (MPS) followed by ICA with conditional FFR. Stratified analysis and uni- and multiple logistic regression analyses were performed to identify predictors of diagnostic agreement between perfusion scans and ICA and predictors of revascularisation. Myocardial ischemia evaluated with perfusion scans was present in 65/292 (22%) while 117/292 (40%) had obstructive CAD evaluated by ICA. Revascularisation rate was 90/292 (31%). The overall sensitivity for perfusion scans was 39% (30-48), specificity 89% (83-93), PPV 69% (57-80) and NPV 68% (62-74). Stratified analysis showed higher sensitivities in patients with multi-vessel disease at CCTA 49% (37-60) and typical chest pain 50% (37-60). Predictors of revascularisation were multi-vessel disease by CCTA (OR 3.51 [1.91-6.48]) and a positive perfusion scan (OR 4.69 [2.49-8.83]). The sensitivity for perfusion scans after CCTA was highest in patients with typical angina and multiple lesions at CCTA and predicted diagnostic agreement between perfusion scans and ICA. Abnormal perfusion and multi vessel disease at CCTA predicted revascularisation.

Restricting glycolysis impairs brown adipocyte glucose and oxygen consumption

During thermogenic activation, brown adipocytes take up large amounts of glucose. In addition, cold stimulation leads to an upregulation of glycolytic enzymes. Here we have investigated the importance of glycolysis for brown adipocyte glucose consumption and thermogenesis. Using siRNA-mediated knockdown in mature adipocytes, we explored the effect of glucose transporters and glycolytic enzymes on brown adipocyte functions such as consumption of glucose and oxygen. Basal oxygen consumption in brown adipocytes was equally dependent on glucose and fatty acid oxidation, whereas isoproterenol (ISO)-stimulated respiration was fueled mainly by fatty acids, with a significant contribution from glucose oxidation. Knockdown of glucose transporters in brown adipocytes not only impaired ISO-stimulated glycolytic flux but also oxygen consumption. Diminishing glycolytic flux by knockdown of the first and final enzyme of glycolysis, i.e., hexokinase 2 (HK2) and pyruvate kinase M (PKM), respectively, decreased glucose uptake and ISO-stimulated oxygen consumption. HK2 knockdown had a more severe effect, which, in contrast to PKM knockdown, could not be rescued by supplementation with pyruvate. Hence, brown adipocytes rely on glucose consumption and glycolytic flux to achieve maximum thermogenic output, with glycolysis likely supporting thermogenesis not only by pyruvate formation but also by supplying intermediates for efferent metabolic pathways.

GSK3 is a negative regulator of the thermogenic program in brown adipocytes

Brown adipose tissue is a promising therapeutic target in metabolic disorders due to its ability to dissipate energy and improve systemic insulin sensitivity and glucose homeostasis. β-Adrenergic stimulation of brown adipocytes leads to an increase in oxygen consumption and induction of a thermogenic gene program that includes uncoupling protein 1 (Ucp1) and fibroblast growth factor 21 (Fgf21). In kinase inhibitor screens, we have identified glycogen synthase kinase 3 (GSK3) as a negative regulator of basal and β-adrenergically stimulated Fgf21 expression in cultured brown adipocytes. In addition, inhibition of GSK3 also caused increased Ucp1 expression and oxygen consumption. β-Adrenergic stimulation triggered an inhibitory phosphorylation of GSK3 in a protein kinase A (PKA)-dependent manner. Mechanistically, inhibition of GSK3 activated the mitogen activated protein kinase (MAPK) kinase 3/6-p38 MAPK-activating transcription factor 2 signaling module. In summary, our data describe GSK3 as a novel negative regulator of β-adrenergic signaling in brown adipocytes.

SYK kinase mediates brown fat differentiation and activation

Brown adipose tissue (BAT) metabolism influences glucose homeostasis and metabolic health in mice and humans. Sympathetic stimulation of β-adrenergic receptors in response to cold induces proliferation, differentiation, and UCP1 expression in pre-adipocytes and mature brown adipocytes. Here we show that spleen tyrosine kinase (SYK) is upregulated during brown adipocyte differentiation and activated by β-adrenergic stimulation. Deletion or inhibition of SYK, a kinase known for its essential roles in the immune system, blocks brown and white pre-adipocyte proliferation and differentiation in vitro, and results in diminished expression of Ucp1 and other genes regulating brown adipocyte function in response to β-adrenergic stimulation. Adipocyte-specific SYK deletion in mice reduces BAT mass and BAT that developed consisted of SYK-expressing brown adipocytes that had escaped homozygous Syk deletion. SYK inhibition in vivo represses β-agonist-induced thermogenesis and oxygen consumption. These results establish SYK as an essential mediator of brown fat formation and function.

Spleen protein tyrosine kinase (Syk) has so far been mainly studied in haematopoietic and immune cells. Here, the authors show that Syk also has a role in brown adipose tissue, where it regulates the formation of brown adipocytes and their thermogenic activation in response to β-adrenergic stimulation.

An siRNA-based method for efficient silencing of gene expression in mature brown adipocytes

Brown adipose tissue is a promising therapeutic target for opposing obesity, glucose intolerance and insulin resistance. The ability to modulate gene expression in mature brown adipocytes is important to understand brown adipocyte function and delineate novel regulatory mechanisms of non-shivering thermogenesis. The aim of this study was to optimize a lipofection-based small interfering RNA (siRNA) transfection protocol for efficient silencing of gene expression in mature brown adipocytes. We determined that a critical parameter was to deliver the siRNA to mature adipocytes by reverse transfection, i.e. transfection of non-adherent cells. Using this protocol, we effectively knocked down both high- and low-abundance transcripts in a model of mature brown adipocytes (WT-1) as well as in primary mature mouse brown adipocytes. A functional consequence of the knockdown was confirmed by an attenuated increase in uncoupled respiration (thermogenesis) in response to β-adrenergic stimulation of mature WT-1 brown adipocytes transfected with uncoupling protein 1 siRNA. Efficient gene silencing was also obtained in various mouse and human white adipocyte models (3T3-L1, primary mouse white adipocytes, hMADS) with the ability to undergo “browning.” In summary, we report an easy and versatile reverse siRNA transfection protocol to achieve specific silencing of gene expression in various models of mature brown and browning-competent white adipocytes, including primary cells.

Repeated Contrast Administration Is Associated With Low Risk of Postcontrast Acute Kidney Injury and Long-Term Complications in Patients With Severe Chronic Kidney Disease

Patients with chronic kidney disease (CKD) frequently require radiographic examinations. We investigated the impact of repeated contrast administrations on short- and long-term kidney function and mortality in kidney transplantation candidates. In a prospective study, 81 predialysis transplantation candidates underwent computed tomography angiography (CTA) and invasive coronary angiography (ICA) as part of a pretransplant cardiovascular evaluation. Postcontrast plasma creatinine (P-creatinine) changes were compared with a precontrast control period. We identified postcontrast acute kidney injury (AKI) in 10 patients (13%) after CTA and in two patients (3%) after ICA. Compared with the control period, relative changes in P-creatinine were significantly higher after CTA (p < 0.001) and ICA (p < 0.01). Diabetic kidney failure (p < 0.05) and contrast dose >0.8 mL/kg (p < 0.001) were associated with increases in P-creatinine. All cases of postcontrast AKI were reversible, and we found no differences between the progression rates of the kidney failure during 12 months before and after contrast exposure (p = 0.56). In a Cox regression analysis, creatinine changes after CTA or ICA were not associated with increased need for dialysis treatment or mortality. Contrast exposure and transient postcontrast AKI did not increase the risk of accelerated CKD progression or the time to initiation of dialysis or death.

p53 regulates expression of uncoupling protein 1 through binding and repression of PPARγ coactivator-1α

The tumor suppressor p53 (TRP53 in mice) is known for its involvement in carcinogenesis, but work during recent years has underscored the importance of p53 in the regulation of whole body metabolism. A general notion is that p53 is necessary for efficient oxidative metabolism. The importance of UCP1-dependent uncoupled respiration and increased oxidation of glucose and fatty acids in brown or brown-like adipocytes, termed brite or beige, in relation to energy balance and homeostasis has been highlighted recently. UCP1-dependent uncoupled respiration in classic interscapular brown adipose tissue is central to cold-induced thermogenesis, whereas brite/beige adipocytes are of special importance in relation to diet-induced thermogenesis, where the importance of UCP1 is only clearly manifested in mice kept at thermoneutrality. We challenged wild-type and TRP53-deficient mice by high-fat feeding under thermoneutral conditions. Interestingly, mice lacking TRP53 gained less weight compared with their wild-type counterparts. This was related to an increased expression of Ucp1 and other PPARGC1a and PPARGC1b target genes but not Ppargc1a or Ppargc1b in inguinal white adipose tissue of mice lacking TRP53. We show that TRP53, independently of its ability to bind DNA, inhibits the activity of PPARGC1a and PPARGC1b. Collectively, our data show that TRP53 has the ability to regulate the thermogenic capacity of adipocytes through modulation of PPARGC1 activity.

Retinoic acid has different effects on UCP1 expression in mouse and human adipocytes

Background

Increased adipose thermogenesis is being considered as a strategy aimed at preventing or reversing obesity. Thus, regulation of the uncoupling protein 1 (UCP1) gene in human adipocytes is of significant interest. Retinoic acid (RA), the carboxylic acid form of vitamin A, displays agonist activity toward several nuclear hormone receptors, including RA receptors (RARs) and peroxisome proliferator-activated receptor δ (PPARδ). Moreover, RA is a potent positive regulator of UCP1 expression in mouse adipocytes.

Results

The effects of all-trans RA (ATRA) on UCP1 gene expression in models of mouse and human adipocyte differentiation were investigated. ATRA induced UCP1 expression in all mouse white and brown adipocytes, but inhibited or had no effect on UCP1 expression in human adipocyte cell lines and primary human white adipocytes. Experiments with various RAR agonists and a RAR antagonist in mouse cells demonstrated that the stimulatory effect of ATRA on UCP1 gene expression was indeed mediated by RARs. Consistently, a PPARδ agonist was without effect. Moreover, the ATRA-mediated induction of UCP1 expression in mouse adipocytes was independent of PPARγ coactivator-1α.

Conclusions

UCP1 expression is differently affected by ATRA in mouse and human adipocytes. ATRA induces UCP1 expression in mouse adipocytes through activation of RARs, whereas expression of UCP1 in human adipocytes is not increased by exposure to ATRA.