Loss-of-function OGFRL1 variants identified in autosomal recessive cherubism families

Cherubism (OMIM 118400) is a rare craniofacial disorder in children characterized by destructive jawbone expansion due to the growth of inflammatory fibrous lesions. Our previous studies have shown that gain-of-function mutations in SH3 domain-binding protein 2 (SH3BP2) are responsible for cherubism and that a knock-in mouse model for cherubism recapitulates the features of cherubism, such as increased osteoclast formation and jawbone destruction. To date, SH3BP2 is the only gene identified to be responsible for cherubism. Since not all patients clinically diagnosed with cherubism had mutations in SH3BP2, we hypothesized that there may be novel cherubism genes and that these genes may play a role in jawbone homeostasis. Here, using whole exome sequencing, we identified homozygous loss-of-function variants in the opioid growth factor receptor like 1 (OGFRL1) gene in 2 independent autosomal recessive cherubism families from Syria and India. The newly identified pathogenic homozygous variants were not reported in any variant databases, suggesting that OGFRL1 is a novel gene responsible for cherubism. Single cell analysis of mouse jawbone tissue revealed that Ogfrl1 is highly expressed in myeloid lineage cells. We generated OGFRL1 knockout mice and mice carrying the Syrian frameshift mutation to understand the in vivo role of OGFRL1. However, neither mouse model recapitulated human cherubism or the phenotypes exhibited by SH3BP2 cherubism mice under physiological and periodontitis conditions. Unlike bone marrow-derived M-CSF-dependent macrophages (BMMs) carrying the SH3BP2 cherubism mutation, BMMs lacking OGFRL1 or carrying the Syrian mutation showed no difference in TNF-ɑ mRNA induction by LPS or TNF-ɑ compared to WT BMMs. Osteoclast formation induced by RANKL was also comparable. These results suggest that the loss-of-function effects of OGFRL1 in humans differ from those in mice and highlight the fact that mice are not always an ideal model for studying rare craniofacial bone disorders.

Clinical and ultrasound features of difficult-to-treat rheumatoid arthritis: A multicenter RA ultrasound cohort study

OBJECTIVE

The optimal strategy for difficult-to-treat (D2T) rheumatoid arthritis (RA) has not been identified, and the ultrasound characteristics of D2T RA have not been reported. We investigated the clinical characteristics and factors contributing to the outcome in D2T RA in a multicentre RA ultrasound observational cohort.

METHOD

We reviewed 307 Japanese patients diagnosed with RA who underwent treatment with biological and targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs). We compared the differences in patient characteristics between the D2T RA and non-D2T RA groups. We examined the factors contributing to a good response [defined as b/tsDMARD continuation and Clinical Disease Activity Index (CDAI) ≤ 10 at 12 months] in the D2T RA patient group.

RESULTS

Forty-three patients (14%) were categorized as D2T RA and the remaining 264 (86%) as non-D2T RA at baseline. The grey-scale (GS) score, disease duration, and CDAI at the initiation of treatment were significantly higher in the D2T RA group than in the non-D2T RA group. In contrast, the power Doppler (PD) score was not significantly different between the two groups. Of the 43 D2T RA patients, 20 achieved a good response. The introduction of CTLA4-Ig (n = 5) was significantly associated with a good response in analysis based on inverse probability weighting with propensity score. GS and PD scores at baseline were not significantly associated with therapeutic response at 12 months in D2T RA patients.

CONCLUSIONS

Patients with D2T RA had high clinical and ultrasound activity and poor responses to treatment with b/tsDMARDs. CTLA4-Ig was associated with a good response at 12 months in D2T RA patients.

Scaffold protein SH3BP2 signalosome is pivotal for immune activation in nephrotic syndrome

Despite clinical use of immunosuppressive agents, the immunopathogenesis of minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) remains unclear. Src homology 3-binding protein 2 (SH3BP2), a scaffold protein, forms an immune signaling complex (signalosome) with 17 other proteins, including phospholipase Cγ2 (PLCγ2) and Rho-guanine nucleotide exchange factor VAV2 (VAV2). Bioinformatic analysis of human glomerular transcriptome (Nephrotic Syndrome Study Network cohort) revealed upregulated SH3BP2 in MCD and FSGS. The SH3BP2 signalosome score and downstream MyD88, TRIF, and NFATc1 were significantly upregulated in MCD and FSGS. Immune pathway activation scores for Toll-like receptors, cytokine-cytokine receptor, and NOD-like receptors were increased in FSGS. Lower SH3BP2 signalosome score was associated with MCD, higher estimated glomerular filtration rate, and remission. Further work using Sh3bp2KI/KI transgenic mice with a gain-in-function mutation showed ~6-fold and ~25-fold increases in albuminuria at 4 and 12 weeks, respectively. Decreased serum albumin and unchanged serum creatinine were observed at 12 weeks. Sh3bp2KI/KI kidney morphology appeared normal except for increased mesangial cellularity and patchy foot process fusion without electron-dense deposits. SH3BP2 co-immunoprecipitated with PLCγ2 and VAV2 in human podocytes, underscoring the importance of SH3BP2 in immune activation. SH3BP2 and its binding partners may determine the immune activation pathways resulting in podocyte injury leading to loss of the glomerular filtration barrier.

Inhibition of RANKL improves the skeletal phenotype of adenine-induced chronic kidney disease in mice

Skeletal fragility and high fracture rates are common in CKD. A key component of bone loss in CKD with secondary hyperparathyroidism is high bone turnover and cortical bone deterioration through both cortical porosity and cortical thinning. We hypothesized that RANKL drives high bone resorption within cortical bone leading to the development of cortical porosity in CKD (study 1) and that systemic inhibition of RANKL would mitigate the skeletal phenotype of CKD (study 2). In study 1, we assessed the skeletal properties of male and female Dmp1-cre RANKLfl/fl (cKO) and control genotype (Ranklfl/fl; Con) mice after 10 wk of adenine-induced CKD (AD; 0.2% dietary adenine). All AD mice regardless of sex or genotype had elevated blood urea nitrogen and high PTH. Con AD mice in both sexes had cortical porosity and lower cortical thickness as well as high osteoclast-covered trabecular surfaces and higher bone formation rate. cKO mice had preserved cortical bone microarchitecture despite high circulating PTH as well as no CKD-induced increases in osteoclasts. In study 2, male mice with established AD CKD were either given a single injection of an anti-RANKL antibody (5 mg/kg) 8 wk post-induction of CKD or subjected to 3×/wk dosing with risedronate (1.2 μg/kg) for 4 wk. Anti-RANKL treatment significantly reduced bone formation rate as well as osteoclast surfaces at both trabecular and cortical pore surfaces; risedronate treatment had little effect on these bone parameters. In conclusion, these studies demonstrate that bone-specific RANKL is critical for the development of high bone formation/high osteoclasts and cortical bone loss in CKD with high PTH. Additionally, systemic anti-RANKL ligand therapy in established CKD may help prevent the propagation of cortical bone loss via suppression of bone turnover.

Osteocyte RANKL Drives Bone Resorption in Mouse Ligature-Induced Periodontitis

Mouse ligature-induced periodontitis (LIP) has been used to study bone loss in periodontitis. However, the role of osteocytes in LIP remains unclear. Furthermore, there is no consensus on the choice of alveolar bone parameters and time points to evaluate LIP. Here, we investigated the dynamics of changes in osteoclastogenesis and bone volume (BV) loss in LIP over 14 days. Time-course analysis revealed that osteoclast induction peaked on days 3 and 5, followed by the peak of BV loss on day 7. Notably, BV was restored by day 14. The bone formation phase after the bone resorption phase was suggested to be responsible for the recovery of bone loss. Electron microscopy identified bacteria in the osteocyte lacunar space beyond the periodontal ligament (PDL) tissue. We investigated how osteocytes affect bone resorption of LIP and found that mice lacking receptor activator of NF-κB ligand (RANKL), predominantly in osteocytes, protected against bone loss in LIP, whereas recombination activating 1 (RAG1)-deficient mice failed to resist it. These results indicate that T/B cells are dispensable for osteoclast induction in LIP and that RANKL from osteocytes and mature osteoblasts regulates bone resorption by LIP. Remarkably, mice lacking the myeloid differentiation primary response gene 88 (MYD88) did not show protection against LIP-induced bone loss. Instead, osteocytic cells expressed nucleotide-binding oligomerization domain containing 1 (NOD1), and primary osteocytes induced significantly higher Rankl than primary osteoblasts when stimulated with a NOD1 agonist. Taken together, LIP induced both bone resorption and bone formation in a stage-dependent manner, suggesting that the selection of time points is critical for quantifying bone loss in mouse LIP. Pathogenetically, the current study suggests that bacterial activation of osteocytes via NOD1 is involved in the mechanism of osteoclastogenesis in LIP. The NOD1-RANKL axis in osteocytes may be a therapeutic target for bone resorption in periodontitis. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Imatinib has minimal effects on inflammatory and osteopenic phenotypes in a murine cherubism model

OBJECTIVE

Cherubism is a genetic disorder characterised by bilateral jawbone deformation. The associated jawbone lesions regress after puberty, whereas severe cases require surgical treatment. Although several drugs have been tested, fundamental treatment strategies for cherubism have not been established. The effectiveness of imatinib has recently been reported; however, its pharmaceutical mechanism remains unclear. In this study, we tested the effects of imatinib using a cherubism mouse model.

METHODS

We used Sh3bp2 P416R cherubism mutant mice, which exhibit systemic organ inflammation and osteopenia. The effects of imatinib were determined using primary bone marrow-derived macrophages. Imatinib was administered intraperitoneally to the mice, and serum tumour necrosis factor-α (TNFα), organ inflammation and bone properties were examined.

RESULTS

The cherubism mutant macrophages produced higher levels of TNFα in response to lipopolysaccharide compared to wild-type macrophages, and imatinib did not significantly suppress TNFα production. Although imatinib suppressed osteoclast formation in vitro, administering it in vivo did not suppress organ inflammation and osteopenia.

CONCLUSION

The in vivo administration of imatinib had a minimal therapeutic impact in cherubism mutant mice. To establish better pharmaceutical interventions, it is necessary to integrate new findings from murine models with clinical data from patients with a definitive diagnosis of cherubism.

Type 1 diabetes mellitus leads to gingivitis and an early compensatory increase in bone remodeling

BACKGROUND

Type 1 diabetes mellitus (T1DM) and periodontitis have long been thought to be biologically connected. Indeed, T1DM is a risk factor for periodontal disease. With the population of diabetic individuals growing, it is more important than ever to understand the negative consequences of diabetes on the periodontium and the mechanisms. The aim of this study was to find out the early effects of T1DM on the periodontium without any experimentally induced periodontitis.

METHODS

We established the streptozotocin (STZ)-induced diabetic mouse model and examined the periodontium 8 weeks later by histology, molecular and cellular assays. Microcomputed tomographic (𝜇CT) imaging and in vivo fluorochrome labeling were also used to quantify bone volume and mineral apposition rates (MAR).

RESULTS

The histologic appearance of epithelium tissue, connective tissue, and periodontal ligament in the diabetic condition was comparable with that of control mice. However, immune cell infiltration in the gingiva was dramatically elevated in the diabetic mice, which was accompanied by unmineralized connective tissue degeneration. Bone resorption activity was significantly increased in the diabetic mice, and quantitative 𝜇CT demonstrated the bone volume, the ratio of bone volume over tissue volume, and cemento-enamel junction to alveolar bone crest (CEJ-ABC) in the diabetic condition were equivalent to those in the control group. In vivo fluorochrome labeling revealed increased MAR and bone remodeling in the diabetic mice. Further investigation found the diabetic mice had more osteoprogenitors recruited to the periodontium, allowing more bone formation to balance the enhanced bone resorption.

CONCLUSIONS

STZ-induced T1DM mice, at an early stage, have elevated gingival inflammation and soft tissue degeneration and increased bone resorption; but still the alveolar bone was preserved by recruiting more osteoprogenitor cells and increasing the rate of bone formation. We conclude that inflammation and periodontitis precede alveolar bone deterioration in diabetes.

Osteocytes directly regulate osteolysis via MYD88 signaling in bacterial bone infection

The impact of bone cell activation on bacterially-induced osteolysis remains elusive. Here, we show that matrix-embedded osteocytes stimulated with bacterial pathogen-associated molecular patterns (PAMPs) directly drive bone resorption through an MYD88-regulated signaling pathway. Mice lacking MYD88, primarily in osteocytes, protect against osteolysis caused by calvarial injections of bacterial PAMPs and resist alveolar bone resorption induced by oral Porphyromonas gingivalis (Pg) infection. In contrast, mice with targeted MYD88 restoration in osteocytes exhibit osteolysis with inflammatory cell infiltration. In vitro, bacterial PAMPs induce significantly higher expression of the cytokine RANKL in osteocytes than osteoblasts. Mechanistically, activation of the osteocyte MYD88 pathway up-regulates RANKL by increasing binding of the transcription factors CREB and STAT3 to Rankl enhancers and by suppressing K48-ubiquitination of CREB/CREB binding protein and STAT3. Systemic administration of an MYD88 inhibitor prevents jawbone loss in Pg-driven periodontitis. These findings reveal that osteocytes directly regulate inflammatory osteolysis in bone infection, suggesting that MYD88 and downstream RANKL regulators in osteocytes are therapeutic targets for osteolysis in periodontitis and osteomyelitis.

Interrelation between baseline plaque characteristics and changes in coronary atherosclerosis with the PCSK9-inhibitor alirocumab: insights from the PACMAN-AMI randomized trial

Background

Patients with acute myocardial infarction (AMI) frequently experience recurrent atherothrombotic events, largely attributable to non-culprit lesions with high-risk characteristics. Statins can halt the progression of coronary atherosclerosis, and addition of protein convertase subtilisin/kexin type 9-inhibitors (PCSK9i) results in incremental low-density lipoprotein cholesterol (LDL-C) lowering and atheroma regression.

Purpose

We sought to examine the interrelation between baseline imaging characteristics, on-treatment LDL-C levels, and changes in coronary atherosclerosis as assessed by serial, multi-modality intracoronary imaging in patients with AMI.

Methods

This is a post hoc analysis from the PACMAN-AMI randomized trial. Patients were randomly allocated to biweekly alirocumab 150 mg vs. placebo on top of high-intensity statin initiated within 24h of presentation with AMI, and underwent serial imaging of the two non-infarct-related arteries at baseline and after 52 weeks. The primary endpoint was percent atheroma volume (PAV) by intravascular ultrasound (IVUS). Powered secondary endpoints were maximal lipid core burden index (maxLCBI4mm) by near-infrared spectroscopy (NIRS) and minimum fibrous cap thickness (FCTmin) by optical coherence tomography (OCT).

Results

Of 300 randomized patients (mean age 58.5±9.8 years, 18.7% women, baseline LDL-C 3.94±0.87 mmol/L), IVUS was serially performed in 265 patients (537 arteries). LDL-C levels decreased to 1.92±0.79 mmol/L with placebo and 0.61±0.61 mmol/L with alirocumab (p<0.001). Compared with placebo (statin alone), alirocumab added to statin resulted in greater PAV reduction (−2.13% vs. −0.92%; p<0.001), greater maxLCBI4mm reduction (−79.42 vs. −37.60; p=0.006), and greater increase in FCTmin (62.67 vs. 33.19 μm; p=0.001). Changes in PAV and maxLCBI4mm were inversely related to on-treatment LDL-C levels, and change in FCTmin was positively related to on-treatment LDL-C levels (Figure 1). Across all patients, we found significant, inverse relationships between change in PAV and baseline PAV [slope: −0.072 (95% CI −0.101 to −0.042); p<0.001], between change in maxLCBI4mm and baseline maxLCBI4mm [slope: −0.437 (95% CI −0.505 to −0.369); p<0.001], and between change in FCTmin and baseline FCTmin [slope: −0.436 (95% CI −0.541 to −0.332); p<0.001]; these findings indicate greater PAV and maxLCBI4mm regression in lesions with greater PAV and LCBI4mm at baseline, and greater fibrous cap thickening in lesions with thinner fibrous caps at baseline.

Conclusion

In this study of intensive LDL-C lowering treatment initiated in the acute AMI setting, more favorable plaque changes were observed in patients with lower on-treatment LDL-C levels and in lesions with more adverse baseline plaque characteristics. Whether AMI patients with high-risk plaque features might derive greater clinical benefit from early initiation of intensive LDL-C-lowering therapies requires further investigation.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Sanofi, Regeneron

Impact of alirocumab added to high-intensity statin therapy on platelet function in AMI patients: a pre-specified substudy of the randomized, placebo-controlled PACMAN-AMI trial

Background

Previous small observational studies have suggested a potential association of proprotein convertase subtilisin kexin type 9 (PCSK9) and platelet reactivity. However, the role of the PCSK9 inhibitor alirocumab on platelet aggregation among patients with acute myocardial infarction (AMI) remains unknown.

Purpose

We investigated the effect of alirocumab on P2Y12 reaction unit (PRU) on top of high-intensity statin therapy among AMI patients receiving dual antiplatelet therapy (DAPT) with a potent P2Y12 inhibitor (ticagrelor or prasugrel).

Methods

This was a pre-specified, powered, pharmacodynamic substudy nested within the PACMAN (effects of the PSCK9 antibody AliroCuMab on coronary Atherosclerosis in patieNts with Acute Myocardial Infarction) trial, a randomized, double-blind trial comparing biweekly alirocumab (150mg) versus placebo in AMI patients undergoing percutaneous coronary intervention (PCI). Patients recruited at Bern University Hospital, receiving DAPT with either ticagrelor or prasugrel at 4 weeks and adherent to the study drug (alirocumab or placebo) were analyzed for the current study. The VerifyNow P2Y12 point-of-care assays were used to measure PRU at baseline (i.e. before first study drug administration), 4 weeks, and 52 weeks after study drug administration (higher PRU levels indicating greater platelet aggregation). The primary endpoint was PRU at 4 weeks.

Results

Among 139 randomized patients (mean age 58.2 years [SD, 9.5], 21 [15.0%] women, mean LDL-C level 150.6mg/dL [SD, 30.9]), baseline characteristics were well balanced between groups including baseline PRU (50.0 [IQR, 120.0] in the alirocumab group vs. 62.0 [IQR, 122.0] in the placebo group, P=0.75). At 4 weeks, mean LDL-C was significantly lower in the alirocumab group (23.5 [SD, 23.7] mg/dL vs. 74.4 [SD, 30.5] mg/dL, P<0.001). The majority of patients received ticagrelor DAPT at 4 weeks (57 [86.4%] vs. 69 [94.5%], P=0.14). There were no significant differences in PRU at 4 weeks (12.5 [IQR, 27.0] vs. 19.0 [IQR, 30.0], P=0.26) and at 52 weeks (25.0 [IQR, 37.0] vs. 34.0 [IQR, 59.0], P=0.07) (Figure). Consistent results were observed in 126 patients treated with ticagrelor (i.e. after excluding 13 patients treated with prasugrel) at 4 weeks (13.0 [IQR, 20.0] vs. 18.0 [IQR, 27.0], P=0.28).

Conclusion

Among AMI patients receiving DAPT with potent P2Y12 inhibitors, alirocumab had no significant effect on platelet function as assessed by PRU.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Bern University Hospital

OC_Finder: Osteoclast Segmentation, Counting, and Classification Using Watershed and Deep Learning

Osteoclasts are multinucleated cells that exclusively resorb bone matrix proteins and minerals on the bone surface. They differentiate from monocyte/macrophage lineage cells in the presence of osteoclastogenic cytokines such as the receptor activator of nuclear factor-κB ligand (RANKL) and are stained positive for tartrate-resistant acid phosphatase (TRAP). In vitro osteoclast formation assays are commonly used to assess the capacity of osteoclast precursor cells for differentiating into osteoclasts wherein the number of TRAP-positive multinucleated cells is counted as osteoclasts. Osteoclasts are manually identified on cell culture dishes by human eyes, which is a labor-intensive process. Moreover, the manual procedure is not objective and results in lack of reproducibility. To accelerate the process and reduce the workload for counting the number of osteoclasts, we developed OC_Finder, a fully automated system for identifying osteoclasts in microscopic images. OC_Finder consists of cell image segmentation with a watershed algorithm and cell classification using deep learning. OC_Finder detected osteoclasts differentiated from wild-type and Sh3bp2KI/+ precursor cells at a 99.4% accuracy for segmentation and at a 98.1% accuracy for classification. The number of osteoclasts classified by OC_Finder was at the same accuracy level with manual counting by a human expert. OC_Finder also showed consistent performance on additional datasets collected with different microscopes with different settings by different operators. Together, successful development of OC_Finder suggests that deep learning is a useful tool to perform prompt and accurate unbiased classification and detection of specific cell types in microscopic images.

Tlr2/4 ‐Mediated Hyperinflammation Promotes Cherubism‐Like Jawbone Expansion in Sh3bp2 ( P416R ) Knockin Mice

Cherubism (CBM), characterized by expansile jawbones with multilocular fibrocystic lesions, is caused by gain‐of‐function mutations in SH3 domain‐binding protein 2 (SH3BP2; mouse orthologue Sh3bp2). Loss of jawbone and dental integrity significantly decrease the quality of life for affected children. Treatment for CBM is limited to multiple surgeries to correct facial deformities. Despite significant advances made with CBM knockin (KI) mouse models (Sh3bp2^KI/KI), the activation mechanisms of CBM lesions remain unknown because mutant mice do not spontaneously develop expansile jawbones. We hypothesize that bony inflammation of an unknown cause triggers jawbone expansion in CBM. To introduce jawbone inflammation in a spatiotemporally controlled manner, we exposed pulp of the first right mandibular molar of 6‐week‐old Sh3bp2^+/+, Sh3bp2^KI/+, and Sh3bp2^KI/KI mice. Bacterial invasion from the exposed pulp into root canals led to apical periodontitis in wild‐type and mutant mice. The pathogen‐associated molecular patterns (PAMPs)‐induced inflammation of alveolar bone resulted in jawbone expansion in Sh3bp2^KI/+ and Sh3bp2^KI/KI mice. CBM‐like lesions developed exacerbated inflammation with increased neutrophil, macrophage, and osteoclast numbers. These lesions displayed excessive neutrophil extracellular traps (NETs) compared to Sh3bp2^+/+ mice. Expression levels of IL‐1β, IL‐6, and TNF‐α were increased in periapical lesions of Sh3bp2^+/+, Sh3bp2^KI/+, and Sh3bp2^KI/KI mice and also in plasma and the left untreated mandibles (with no pulp exposure) of Sh3bp2^KI/KI mice, suggesting a systemic upregulation. Ablation of Tlr2/4 signaling or depletion of neutrophils by Ly6G antibodies ameliorated jawbone expansion induced by PAMPs in Sh3bp2^KI/KI mice. In summary, successful induction of CBM‐like lesions in jaws of CBM mice is important for studying initiating mechanisms of CBM and for testing potential therapies. Our findings further emphasize a critical role of host immunity in the development of apical periodontitis and the importance of maintaining oral health in CBM patients. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Frequency and prognostic impact of periprocedural myocardial infarction determined by various MI definitions in patients with chronic coronary syndromes undergoing percutaneous coronary intervention

Background

Several definitions of peri-procedural myocardial infarction (MI) requiring different biomarker thresholds with or without ancillary criteria for myocardial ischemia are currently recommended without being fully validated in real-world patients with chronic coronary syndrome (CCS) undergoing percutaneous coronary intervention (PCI).

Objectives

We aimed to evaluate the prevalence and prognostic value of high-sensitivity cardiac troponin-based peri-procedural MI according to contemporary MI definitions using a large real-world PCI cohort.

Methods

In CCS patients undergoing elective PCI enrolled to the Bern PCI registry (NCT02241291) between 2010 and 2018, peri-procedural myocardial injury and infarction were assessed according to the 4th and 3rd universal definition of MI (UDMI), academic research consortium (ARC)-2, and Society for Cardiovascular Angiography and Interventions (SCAI) criteria. The primary endpoint was cardiac death at 1 year.

Results

Among 4404 CCS patients, peri-procedural MI defined by the 4th UDMI, 3rd UDMI, ARC-2, and SCAI were observed in 14.9%, 18.0%, 2.0%, and 2.0% of patients, respectively. Cardiac mortality at 1 year in patients with peri-procedural MI defined by 4th UDMI, 3rd UDMI, ARC-2, and SCAI were 3.0%, 2.9%, 5.8%, and 10.0%, respectively. After multivariate adjustments, peri-procedural MI defined by the ARC-2 and SCAI were independently associated with cardiac death at 1 year, while those defined by the 4th and 3rd UDMI were not.

Conclusion

Among CCS patients undergoing PCI, periprocedural MIs defined by theARC-2 and SCAI occurred 7 to 9 times less frequently as compared with the 4th and 3rd UDMI, and were the only definitions significantly associated with cardiac mortality.

Funding Acknowledgement

Type of funding sources: None. Cardiac death at 1 year

Comprehensive non-invasive and invasive functional assessment of anomalous coronary arteries with anatomical high-risk features

Background

Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital disease associated with an increased risk of myocardial ischemia. In AAOCA, the occurrence of ischemia is based on the extent of a fixed and a dynamic component, each attributed to different anatomical high-risk features (i.e., acute take-off angle, slit-like ostium, proximal narrowing, elliptic vessel shape and intramural course). Coronary computed tomography angiography (CCTA) is the primary non-invasive imaging method to depict the presence and quantitatively assess anatomical high-risk features while invasive physiologic evaluation under maximal dobutamine-volume challenge is the gold standard to unravel the hemodynamic relevance of AAOCA.

Methods

We included all consecutive AAOCA patients with anatomical high-risk features from our prospective, open-label registry. The objective is to quantify anatomical high-risk features in the CCTA and to measure hemodynamic relevance using invasive fractional flow reserve with maximal dobutamine-volume challenge (gradually increasing dose of dobutamine max. 40 μg/kg per body weight/min, max. 3000 mL ringer lactate and max. 1mg atropine). Pathological invasive FFR was defined as FFR Dobutamine<0.80. Additionally, CCTA-data were processed to assess computational fluid dynamics (CT FFR) and intravascular ultrasound (IVUS) was used to determine minimal lumen area (MLA) during baseline and maximal stress conditions.

Results

A total of 11 patients were included between 05/19 and 11/2020. Mean age was 59±13 years (range: 40–79), 10 patients showed a right-AAOCA and one patient showed a single right coronary artery. All patients had either one (i.e., in 1 patient) or more than one anatomical-high risk features (i.e., in 10 patients). Mean invasive FFR Dobutamine was 0.88±0.07 with n=2 (18%) being pathological. Mean non-invasive CT FFR was 0.89±0.04 (FFR<0.80; n=0), mean invasive FFR Adenosine was 0.92±0.06 (FFR<0.80; n=1; 9%). There was a significant decrease in IVUS MLA between rest (7.93±2.79mm2) and under dobutamine-volume challenge (6.57±3.20mm2, p=0.008). Mean percentage of MLA reduction was 19±18%.

Conclusion

Our preliminary results provide evidence that relevant myocardial ischemia seems to be often absent in a middle-aged population with AAOCA and anatomical high-risk features. However, in a minority of cases hemodynamic relevance could be depicted, especially when stressing with dobutamine-volume challenge. The presence of a dynamic component in AAOCA is represented by the reduced minimal lumen area under stress conditions. Comprehensive diagnostic evaluation should be performed to prevent unnecessary guideline recommended open-heart surgery in a middle-aged population with AAOCA.

Funding Acknowledgement

Type of funding sources: None.

Derivation and validation of myocardial bridge characteristics by optical coherence tomography: a prospective multimodality imaging study

Background

Optical coherence tomography (OCT) findings of myocardial bridge (MB) have not been established.

Purpose

We aimed to establish the OCT appearance of MB compared with the half-moon sign derived by intravascular ultrasound (IVUS) and to assess the prevalence among patients undergoing coronary angiography and OCT in clinical practice.

Methods

For derivation of the OCT appearance of MB, imaging data obtained from 122 patients undergoing OCT and IVUS for the left anterior descending artery (LAD) enrolled in two prospective imaging studies were analyzed. To assess the prevalence of OCT-derived MB, 470 patients undergoing OCT for LAD in clinical routine were analyzed.

Results

We found a homogeneous band with intermediate light intensity surrounding the vessel wall as assessed by OCT corresponding to half-moon sign derived by IVUS. Mean length, angle, and thickness of OCT-MB were 21.2±10.8mm, 205.7±56.5°, and 0.39±0.06mm, respectively. Mean length of IVUS-MB was significantly longer as compared with OCT-MB (23.7±11.9, P=0.010), while there were no significant differences in angle and thickness. MB angle was >180° in approximately 50% of frames with MB. There was a strong/moderate correlation between OCT-MB and half-moon sign (MB length: r=0.81, P=0.001, MB angle: r=0.58, P=0.001). In the derivation cohort, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of OCT-MB for the milking effect by angiography were 96.3%, 62.1%, 41.9%, 98.3%, and 69.7%, respectively, and much comparable with the IVUS half-moon sign. In the validation cohort, OCT-detected MB was observed in 139 (29.6%) patients, of whom 57.6% (n=80) did not have angiographic evidence of milking effect.

Conclusion

OCT is able to identify IVUS-defined MB as homogenous band with intermediate light intensity surrounding the vessel wall. There was a high concordance in terms of MB angle and thickness between OCT and IVUS. In clinically-indicated OCT cases of the LAD, more than half of OCT-MBs were angiographically silent. OCT assessment of MB may facilitate the accurate diagnosis of MB and thus provide useful information in determining the subsequent treatment strategy for the patients with MB.

Funding Acknowledgement

Type of funding sources: None. Representative imaging of MBCase of OCT-MB without milking effect

Cardio-ankle vascular index is useful screening method to detect obstructive coronary artery disease in asymptomatic diabetes patients with subclinical atherosclerosis

Background

Patients with diabetes mellitus are at very high risk for obstructive coronary artery disease; however, invasive coronary angiography is not allowed to apply in all patients. Cardio-ankle vascular index (CAVI), a marker of arterial stiffness has been reported to reflect atherosclerotic burden.

Purpose

To assess the diagnostic performance of CAVI vs. coronary calcium score for detecting obstructive coronary artery disease determined by Coronary CT angiography (CCTA) in asymptomatic diabetes patients.

Methods

During May 2015 to December 2019, 816 patients with diabetes mellitus were evaluated. First, intima-media thickness of carotid artery was measured in all subjects. Then, patients with intima-media thickness over 11mm underwent CAVI. Finally, 209 patients who have one or more cardiovascular risk factors other than diabetes mellitus were enrolled (68±11 years, 68% men). Patients were excluded if they had a disorder of the kidney, a prior history of coronary artery revascularization, atrial fibrillation, LV ejection fraction <50%, ABI <0.9 or allergy to contrast. Diagnostic performance of CAVI was evaluated with coronary stenosis >50% by CCTA.

Results

CAVI, Agatston score, and intima-media thickness of carotid artery were 9.2±1.3, 396±621 and 2.0±0.7mm, respectively. CAVI was significantly correlated with age (r=0.530, p<0.001), coronary artery calcification (r=0.182, p=0.008), and intima-media thickness of carotid artery (r=0.195, p=0.005). Among them, 108 patients (48%) had coronary stenosis. CAVI, Agatston score and intima-media thickness of carotid artery in patients with coronary stenosis were higher than that without coronary stenosis, respectively (9.8±1.1 vs 8.5±1.0, p<0.001, 526±676 vs. 255±525, p=0.001, 2.2±0.7 vs. 1.8±0.6, p<0.001). The ROC curve analysis of CAVI for discriminating coronary stenosis showed that the sensitivity 75.0% and specificity 77.2% at the cut off value of 9.23 (AUC=0.812, p<0.001). Contrastingly, diagnostic performance of coronary calcium score and intima-media thickness of carotid artery were less than CAVI (sensitivity: 91.7%, specificity: 56.4%, AUC=0.753, p<0.05 vs. CAVI, sensitivity: 68.5%, specificity: 59.4%, AUC=0.663, p<0.05 vs. CAVI). Multivariate logistic analysis demonstrated that CAVI was significantly associated with coronary stenosis (OR=4.133, p<0.001) after adjustment of conventional risk factors, although coronary calcium score was not correlated with coronary stenosis.

Conclusion

CAVI could be informative to select patients having obstructive coronary artery disease in asymptomatic diabetes patients with thick intima-media thickness.

Funding Acknowledgement

Type of funding sources: None.

Ultrasound efficacy of targeted-synthetic disease-modifying anti-rheumatic drug treatment in rheumatoid arthritis: a multicenter prospective cohort study in Japan

OBJECTIVE

This study investigated the effectiveness of treatment with Janus kinase (JAK) inhibitors in rheumatoid arthritis (RA) assessed by ultrasonography (US) activity, and the influence of patient characteristics and previous treatments.

METHOD

This prospective study assessed 60 treatment initiations among 53 Japanese patients diagnosed with RA who underwent treatment with JAK inhibitors during June 2013 to February 2020. Of the 53 patients, seven patients were enrolled in duplicate because they were treated with two different JAK inhibitors at different periods. For each case, the improvement rate on the power Doppler (PD) score was assessed at 6 month follow-up. Median improvement rate of PD score was used to classify cases as either US responders or non-responders, and patient characteristics were compared between the two groups.

RESULTS

All indicators of clinical disease activity and US activity showed a significant improvement at 3 months compared with baseline. Although the JAK inhibitor-cycler group and the interleukin-6 (IL-6) inhibitor inadequate response (IR) group tended to show a later improvement for US activity, all indicators of clinical disease activity and US activity showed a significant improvement at 6 months compared with baseline for both groups. Multivariate analysis showed that concomitant methotrexate use and an IR to the previous biologic or targeted-synthetic disease-modifying anti-rheumatic drug (b/tsDMARD) treatment were independently and significantly associated with US responders.

CONCLUSION

Use of a JAK inhibitor in combination with methotrexate and an absence of IR to any previous b/tsDMARDs demonstrated superior effectiveness for patients with RA.

POS0674 DIRECT COMPARISON OF EFFECTIVENESS AND SAFETY OF TOFACITINIB AND BARICITINIB IN PATIENTS WITH RHEUMATOID ARTHRITIS IN REAL-WORLD SETTINGS

Background:

Tofacitinib is a non-selective first-generation JAK inhibitor and baricitinib was approved for the treatment of Rheumatoid arthritis several years after approve of tofacitinib. Randomized controlled trials have shown good treatment response for RA in these two drugs. However, the evaluation of these two drugs in real-world setting have been rarely reported, moreover, until now, no published data of a direct comparison among JAK inhibitors in RA have been available.

Objectives:

To compare the efficacy and safety of the JAK inhibitors tofacitinib and baricitinib in patients with rheumatoid arthritis (RA) by using propensity score matching in a real-world setting.

Methods:

A total of 242 patients with RA who were treated with tofacitinib (n=161) or baricitinib (n=81) were enrolled. To avoid confounding, we performed propensity score matching based on multiple baseline characteristic variables, and then 80 baricitinib-treated patients and 57 tofacitinib-treated patients were extracted for the direct comparison. A mixed effect model with a repeated measures analysis of variance (ANOVA) was performed to ascertain whether there were significant differences in clinical efficacy between the two treatment groups during the treatment period.Finally, We evaluated the predictive factor of clinical responses by performing univariate and multivariable logistic regression analyses.

Results:

The mean delta disease activity scores (DAS)28-ESR from baseline to 6 months were −1.60 (tofacitinib) and −1.46 (baricitinib). The remission rate defined by the DAS28-ESR at 24 weeks were 21.1% (tofacitinib) and 25.0% (baricitinib). There was no significant difference in the clinical response between the baricitinib-treated and tofacitinib-treated groups. Although there was no significant difference, the concomitant use of methotrexate (MTX) showed better clinical efficacy in the cases of baricitinib treatment as compared with in the case of tofacitinib treatment. In both groups, the most common AE was herpes zoster infection, and the AE rates were similar between the two groups. However, the predictive factors contributing to clinical response differed. The concomitant use of oral steroid was independently associated with the achievement of DAS-low disease activity in both groups, whereas in the baricitinib group, the number of biological and/or targeted synthetic DMARDs previously used and the DAS28-ESR at the time of initiation were associated with DAS-low disease activity.

Conclusion:

This study indicate that tofacitinib and baricitinib had comparable efficacies and safety profiles in a real-world setting. However, the influence of clinical characteristics on the treatment response differed between these two drugs. Direct comparison between two JAK inhibitors provide useful information to optimal use of JAK inhibitors in real-world settings.

Disclosure of Interests:

None declared

Discrepancy between clinical and ultrasound remissions in rheumatoid arthritis: a multicentre ultrasound cohort study in Japan

Objectives: Using multicentre ultrasound (US) cohort data among patients with rheumatoid arthritis (RA), we aimed to identify baseline factors that permit differentiation between two patient cohorts achieving US remission and clinical remission, and to determine the factors contributing to the discrepancy.Method: We reviewed 248 Japanese patients diagnosed with RA who underwent treatment with biological disease-modifying anti-rheumatic drugs at 13 centres. We performed US assessments of the synovia of 22 joints. We assessed the percentages of patients with clinical remission and US remission, defined as total power Doppler scores of 0 at 12 months.Results: The 87 patients who achieved US remission were divided into a group that achieved both clinical and US remission (n = 53) and a group that achieved US remission only (n = 34). Baseline factors that were significantly and independently associated with clinical remission at 12 months among patients who also achieved US remission included short disease duration, the presence of concomitant methotrexate use, and low patient global assessment score (p < 0.05, p < 0.05, and p < 0.005, respectively).Conclusions: RA patients with baseline high patient global assessment scores and long disease duration at baseline were unlikely to achieve clinical remission even after achieving US remission. Objective joint assessments using US provide additional information of potential importance for the management of RA.

Changes in right ventricular deformation during hyperoxia versus normoxaemia in patients with stable coronary artery disease and healthy controls

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Local research funds of the Department of Anaesthesiology and Pain medicine, Bern University Hospital, Inselspital

Background

During anaesthesia, emergency and critical care treatment, patients with coronary artery disease (CAD) are often exposed to supraphysiologic arterial oxygen tensions. The balance between benefits and risks of hyperoxia (HO) in patients with stable CAD is controversial, with reports about reduced left ventricular contractility or increased morbidity and mortality. Effects of HO on right ventricular (RV) function in CAD are less well described. Advanced cardiovascular magnetic resonance (CMR) feature tracking software allows assessment of myocardial deformation, which may serve as early marker of ventricular dysfunction. In a CMR study we quantified the effect of HO on RV function and deformation in awake healthy participants and CAD patients.

Methods

Ten healthy participants and 26 patients with stable one- or two-vessel obstructive CAD were included. In a CMR study, a short-axis function stack of both ventricles was obtained first at room air (RA), then during HO induced by breathing oxygen at 10L/min for 5 minutes via a non-rebreathing facemask. RV strain was analysed by a blinded reader who manually traced epicardial and endocardial contours of the RV for determining peak global circumferential strain (RVGCS), time to peak strain, systolic and diastolic strain rate parameters.

Results

RV ejection fraction did not change with O2 breathing in the healthy control group (RA, 56 ± 12% vs. HO, 55 ± 10%, p = 0.999) nor in the CAD group (RA, 60 ± 8% vs. HO, 60 ± 9%, p = 0.609). RV cardiac index decreased significantly in CAD patients from RA (2.62 ± 0.88 L/min/m2) to HO (2.42 ± 0.77L/min/m2, p = 0.002). The decrease in the control group was not significant (RVCI: RA 3.28 ± 1.29 vs HO 3.04 ± 1.27L/min/m2 p = 0.068).

In the healthy control group, RVGCS, time to peak strain, and systolic strain rate did not change significantly with HO (RVGCS: RA, -14.6 ± 3.9% vs. HO, -13.1 ± 4.5%, p = 0.353; time to peak strain: 282 ± 45ms vs. 286 ± 29ms, p = 0.540; and systolic strain rate: -0.85 ± 0.27/s vs. -0.67 ± 0.28, p = 0.055).

In CAD patients RVGCS worsened from -14.8 ± 3.3% on RA to -13.9 ± 3.6% at HO (p = 0.040). Time to peak strain became significantly prolonged from 319 ± 40ms on RA to 329 ± 49ms at HO (p = 0.046). This was accompanied by a reduction of systolic strain rate from -0.79 ± 0.27/s to -0.75 ± 0.22/s (p = 0.037). Diastolic strain parameters did not differ significantly between RA and HO in either group.

Conclusion

In our cohort of CAD patients HO significantly reduced RV cardiac index and impaired systolic deformation as determined by CMR feature tracking. Studies are required in a larger patient cohort with regional analysis and assessment of longitudinal and radial deformation to assess the role of hyperoxia in CAD.

Abstract Figure. Change in RV Peak Circumferential Strain

Post-procedural high platelet reactivity with prasugrel loading predicts in-hospital adverse events in ACS patients

Background/Introduction

High platelet reactivity (HPR) is associated with adverse cardiovascular events, primarily intrastent thrombosis, after a percutaneous coronary intervention (PCI). However, the relationship between hyperacute postprocedural HPR with prasugrel loading and clinical outcomes in acute coronary syndrome (ACS) remains unclear. Moreover, factors contributing to HPR in ACS with prasugrel loading are also unknown.

Purpose

To assess the effects of post-procedural HPR with prasugrel loading on clinical outcomes in ACS during hospitalization, and to define the appropriate cut-off values and identify factors contributing to HPR.

Methods

A single-center, retrospective observational study that enrolled 154 patients who underwent emergent PCI for ACS with prasugrel loading was performed. The P2Y12 reaction unit (PRU) value was measured immediately after PCI using the VerifyNowR system. The primary end-point was major adverse cardiac events (MACE, defined as the composite of death, myocardial infarction, stroke, heart failure, ventricular arrhythmia needing defibrillation).

Results

The mean patient age (standard deviation) was 70.7 (±12.5) years, 76.6% were men, and the average time from the prasugrel intake to PRU calculation was 103.2 (±48.5) min. During the mean hospital stay of 15.6 (±8.5) days, 24 in-hospital MACE (15.5%) and 8 deaths (5.2%) occurred. Thrombosis events, including myocardial infarction recurrence, did not occur (only one case of spontaneous coronary artery dissection was considered as myocardial infarction recurrence). PRU was significantly higher in the MACE group than that in Non-MACE group (287±55 and 232±64, respectively, p&lt;0.001). The ROC curve analysis of PRU for discriminating the significant in-hospital MACE showed the cut-off value of 293 (sensitivity: 62.5%, specificity: 83.1% [AUC=0.756, p&lt;0.0001]). A total of 37 patients (24%) were thus categorized as HPR (PRU&gt;293) immediately after the emergent PCI. Kaplan-Meier curve showing MACE events occurred in the HPR group than that in the non-HPR group (40.5% vs 7.6%, p&lt;0.001). Multiple cox analysis demonstrated that HPR was independent predictors of MACE in patients with ACS who underwent PCI (OR 11.01, 95% CI 2.39–20.2, p&lt;0.0001). Multiple logistic regression model showed old age, female sex, low systolic blood pressure, short prasugrel intake to measure time, and large acute gain were independent predictors of HPR.

Conclusion

PRU was significantly higher in the MACE group, with an appropriate cut-off value of HPR of 293 in this study. HPR was an independent predictor of MACE during hospitalization; however, thrombosis events were not significant. HPR predictors were old age, female sex, low systolic blood pressure, short prasugrel intake to measure time, and large acute gain. This study shows the post-procedural HPR with prasugrel loading in patients with ACS can be a useful predictive marker of adverse events during hospitalization.

Funding Acknowledgement

Type of funding source: None

Cardio-ankle vascular index as an arterial stiffness marker improves on cardiovascular events by adding to framingham risk score

Background

The cardio-ankle vascular index (CAVI) is a non-invasive measurement that evaluates arterial stiffness using the analysis of oscillometric waveform during cuff-Inflation. Several studies reported that CAVI is associated with cardiovascular risk factors, while the clinical prognostic value of CAVI as a surrogate marker of atherosclerosis has not been fully elucidated. Meanwhile, the Framingham risk score (FRS) is an established marker of cardiovascular outcomes.

Purpose

To investigate whether adding CAVI to Framingham risk score improves the prediction of cardiovascular events.

Methods

This prospective observational study included consecutive 422 patients with cardiovascular risk factors but without known coronary artery disease (69±8 years, 63% men). CAVI was measured by the oscillometric method with VaSera vascular screening system. Patients with atrial fibrillation, left ventricular ejection fraction &lt;50%, both ABI&lt;0.9, severe valvular diseases, or hemodialysis were excluded. Primacy outcomes were cardiovascular death, myocardial infarction, stroke, hospitalization for heart failure and revascularization.

Results

During a median follow-up of 3.1 years, cardiovascular events occurred in 12.8% (3.3%, 15.7%, and 19.1% in the low, intermediate and high-risk group of stratification by FRS, respectively). The ROC curve analysis for discriminating cardiovascular events showed that the AUC of CAVI added to Framingham risk score was the highest compared to Framingham risk score and CAVI alone (CAVI added to Framingham risk score: AUC 66.9, 95% CI 59.6–74.2, Framingham risk score alone: AUC 61.5, 95% CI 53.8–69.1, CAVI alone: AUC 62.3, 95% CI 54.1–70.6). The logistic regression analysis demonstrated that CAVI and Framingham risk score were independent predictors of cardiovascular events (CAVI: OR 1.381, 95% CI 1.164–1.597, p=0.004, Framingham risk score: OR 1.135, 95% CI 1.044–1.225, p=0.007). Next, when logistic regression analysis was performed simultaneously on Framingham risk factor and CAVI, CAVI was an independent predictor of cardiovascular events (OR 1.347, 95% CI 1.124–1.569, p=0.009). Furthermore, in the likelihood ratio test, CAVI added to Framingham risk score significantly improved the cardiovascular event prediction ability than Framingham risk factor alone. Next, when patients with intermediate risk (n=217) were divided into two groups based on CAVI of 9.0, the Kaplan-Meier estimate showed that events occurred more frequently in higher CAVI group (9.3% and 29.1%, log-rank, P=0.009) and the C-statistic was 0.662. Multiple Cox analysis showed that, in the intermediate risk group, CAVI was an independent predictor of primary outcomes (HR 1.387 per 1 index, 95% CI 1.081–1.779, p=0.010).

Conclusion

The measurement of CAVI could be a useful predictor for cardiovascular events. In addition, the combination of CAVI and Framingham risk score could improve the predictability compared to the Framingham risk score alone.

Funding Acknowledgement

Type of funding source: None

Prognostic value of intracoronary imaging-derived measures for non-infarct related vessel revascularization throughout 7 years among patients with ST-elevation myocardial infarction

Background

Underlying plaque characteristics that lead to future revascularization during long-term follow-up remain poorly understood.

Purpose

We aimed to explore intracoronary imaging-derived measures as assessed by intravascular ultrasound (IVUS) and optical coherence tomography (OCT) associated with non-infarct related vessel revascularization (non-TVR) arising from imaged segments during long-term (up to 7 years) follow-up among patients with ST-elevated myocardial infarction (STEMI).

Methods

A total of 94 STEMI patients enrolled into the IBIS-4 (Integrated Biomarker Imaging Study-4) study undergoing serial (baseline and 13 months) IVUS and OCT in 2 non-infarct-related coronary arteries under high-intensity statin therapy were analyzed in the present study. Patients were divided into 2 groups according to the occurrence of non-TVR within previously imaged vessel segments (non-TVR: n=14, no non-TVR: n=80).

Results

Baseline characteristics including LDL level were comparable between groups. At baseline, lesions with future non-TVR were associated with greater percent atheroma volume by IVUS (55.6±5.4% vs. 49.6±6.1%, P&lt;0.001), minimum lumen area by OCT (3.4±1.7 mm2 vs. 6.0±3.3 mm2, P=0.004), and a higher prevalence of fibroatheroma (60.0% vs. 20.1%, P=0.007) by OCT compared with those without. Among patients with serial imaging, lesions with non-TVR had a trend towards a less reduction of percent atheroma volume (−0.2±3.8% vs. −2.4±4.2%, P=0.083).

Conclusion

Greater plaque burden, smaller lumen area, and higher prevalence of OCT-detected fibroatheroma at baseline were associated with non-infarct related vessel revascularization. Lesions with non-TVR tend to have less-pronounced regression of coronary atheroma despite intensive statin therapy and achieved LDL levels.

Non-TVR 7 years after index PCI

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation

Quantitative flow ratio to predict non-target-vessel-related events at 5 years in STEMI patients undergoing angiography-guided revascularization

Background

In patients with ST-segment-elevation myocardial infarction (STEMI), angiography-based complete revascularization is associated with superior outcomes compared with culprit-lesion-only percutaneous coronary intervention (PCI). Quantitative Flow Ratio (QFR) is a novel, non-invasive, vasodilator-free method to assess the hemodynamic significance of coronary stenoses.

Purpose

To investigate the incremental value of QFR over angiography alone in the assessment of non-culprit lesions (NCL) in STEMI patients undergoing primary PCI.

Methods

In the randomized, multicenter COMFORTABLE AMI trial, STEMI patients underwent angiography-guided complete revascularization. QFR was determined in untreated non-target vessels by assessors blinded for clinical outcomes.

Results

Out of 1161 STEMI patients, 946 vessels in 617 patients could be analyzed by QFR. At 5-year follow-up, the rate of the primary endpoint cardiac death, non-target vessel myocardial infarction (non-TV-MI) and clinically indicated, non-target vessel revascularization (non-TVR) was significantly higher in patients with QFR ≤0.80 compared with QFR &gt;0.80 (62.9% vs. 12.7%, HR 7.20, 95% CI 4.46–11.62, p&lt;0.001), driven by higher rates of non-TV-MI (15.4% vs. 3.6%, HR 4.59, 95% CI 1.72–12.23, p=0.002) and non-TVR (58.6% vs. 7.7%, HR 10.99, 95% CI 6.39–18.91, p&lt;0.001). No significant differences for cardiac death were observed. Multivariate analysis identified QFR ≤0.80, MI SYNTAX score and left ventricular function as independent predictors of the primary endpoint. QFR ≤0.80 showed an accuracy of 86.1%, sensitivity of 23.2%, specificity of 97.5%, positive predictive value of 62.9% and negative predictive value of 87.5% for the prediction of the primary endpoint.

Conclusions

Our study results suggest incremental value of QFR over angiography-guided PCI for NCL among STEMI patients undergoing primary PCI.

Kaplan-Meier curves of primary endpoint

Funding Acknowledgement

Type of funding source: None

Significance of anti-Ro/SSA antibodies in the response and retention of abatacept in patients with rheumatoid arthritis: a multicentre cohort study

Objective: To determine whether the positivity of baseline anti-Ro/Sjögren's syndrome antigen A (SSA) antibodies influences the response to abatacept, we compared therapeutic responses between anti-Ro/SSA antibody-negative and -positive patients with rheumatoid arthritis (RA) using a multicentre RA ultrasonography prospective cohort. Method: We reviewed Japanese patients with RA who started abatacept as the first biological disease-modifying anti-rheumatic drug between June 2013 and April 2018. We assessed 28-joint Disease Activity Score-erythrocyte sedimentation rate (DAS28-ESR) change between baseline and 6 or 12 months after treatment in RA patients treated with abatacept, and European League Against Rheumatism (EULAR) response at 6 and 12 months. The Global OMERACT-EULAR Synovitis Score (GLOESS) was calculated at baseline and at 6 and 12 months. Results: Overall, 51 patients were enrolled and divided into anti-Ro/SSA antibody-negative and -positive groups of 35 and 16, respectively. Median age at baseline was significantly higher in the anti-Ro/SSA antibody-negative group (p = 0.04). The retention rate and percentage of EULAR good responders at 12 months were significantly higher in the anti-Ro/SSA antibody-negative group (both p = 0.02). Anti-Ro/SSA antibody-negative patients exhibited larger decreases in both DAS28-ESR and DAS28-C-reactive protein at 12 months than anti-Ro/SSA antibody-positive patients (p = 0.02 and 0.04, respectively). GLOESS decreased significantly at 6 months in anti-Ro/SSA antibody-negative patients (p = 0.03). Multivariate analyses showed that anti-Ro/SSA antibody positivity was an independent factor associated with change in the DAS28-ESR at 6 months (p < 0.05). Conclusion: Anti-Ro/SSA antibody positivity predicts a poor response to abatacept and low retention rate.

Microbe-Dependent Exacerbated Alveolar Bone Destruction in Heterozygous Cherubism Mice

Cherubism (OMIM#118400) is a craniofacial disorder characterized by destructive jaw expansion. Gain‐of‐function mutations in SH3‐domain binding protein 2 (SH3BP2) are responsible for this rare disorder. We have previously shown that homozygous knock‐in (KI) mice (Sh3bp2^KI/KI) recapitulate human cherubism by developing inflammatory lesions in the jaw. However, it remains unknown why heterozygous KI mice (Sh3bp2^KI/+) do not recapitulate the excessive jawbone destruction in human cherubism, even though all mutations are heterozygous in humans. We hypothesized that Sh3bp2^KI/+ mice need to be challenged for developing exacerbated jawbone destruction and that bacterial stimulation in the oral cavity may be involved in the mechanism. In this study, we applied a ligature‐induced periodontitis model to Sh3bp2^KI/+ mice to induce inflammatory alveolar bone destruction. Ligature placement induced alveolar bone resorption with gingival inflammation. Quantification of alveolar bone volume revealed that Sh3bp2^KI/+ mice developed more severe bone loss (male: 43.0% ± 10.6%, female: 42.6% ± 10.4%) compared with Sh3bp2^+/+ mice (male: 25.8% ± 4.0%, female: 30.9% ± 6.5%). Measurement of bone loss by the cement‐enamel junction–alveolar bone crest distance showed no difference between Sh3bp2^KI/+ and Sh3bp2^+/+ mice. The number of osteoclasts on the alveolar bone surface was higher in male Sh3bp2^KI/+ mice, but not in females, compared with Sh3bp2^+/+ mice. In contrast, inflammatory cytokine levels in gingiva were comparable between Sh3bp2^KI/+ and Sh3bp2^+/+ mice with ligatures. Genetic deletion of the spleen tyrosine kinase in myeloid cells and antibiotic treatment suppressed alveolar bone loss in Sh3bp2^KI/+ mice, suggesting that increased osteoclast differentiation and function mediated by SYK and accumulation of oral bacteria are responsible for the increased alveolar bone loss in Sh3bp2^KI/+ mice with ligature‐induced periodontitis. High amounts of oral bacterial load caused by insufficient oral hygiene could be a trigger for the initiation of jawbone destruction in human cherubism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

AB0344 FACTORS WHICH CONTRIBUTE PERSISTENCY AND OPTIMAL USE OF TOFACITINIB; LESSONS FROM LONG TERM DAILY CLINICAL USE OF TOFACITINIB

Background:

Recently, tofacitinib treatment in rheumatoid arthritis (RA) is thought to be not inferior to other biologic disease-modifying antirheumatic drugs (bDMARDS) such as TNF-inhibitor. However, approval of tofacitinib for treatment with RA is relatively recent as compared to other bDMARDs, therefore until now, little knowledge about long term efficacy and safety of tofacitinib in real-world settings or about which patients should be initiated tofacitinib are available. Thus, we need evidence from real-world setting for optimal use of tofacitinib.

Objectives:

To investigate the efficacy and safety of tofacitinib and to identify factors which contribute persistency and efficacy of tofacitinib treatment during 2 years.

Methods:

148 patients, for whom tofacitinib was initiated until January 2018 were enrolled. All patients received 5 mg of tofacitinib twice daily and were followed for 2 years. Clinical disease activity indicated by disease activity score (DAS)28-ESR as well as adverse events (AEs) were evaluated. Statistical analysis was performed to determine which baseline variables influenced the persistency and efficacy of tofacitinib.

Results:

92 patients (62.2 %) continued tofacitinib for 2 years. Clinical disease activity rapidly and significantly decreased, and this efficacy continued throughout the 2 years: i.e., DAS28-ESR decreased from 5.13 ± 1.42 at baseline to 4.02 ± 1.11 at 4 weeks and 3.91 ± 1.32 at 2 years (P<0.0001, vs. baseline). 55 AEs including 22 herpes zoster infection occurred during tofacitinib treatment. 27 patients discontinued tofacitinib due to lack of efficacy. Multivariable logistic analysis showed that the number of bDMARDs previously used and age were associated with discontinuation of tofacitinib treatment due to lack of efficacy(table 1). Another set of multivariable logistic analysis revealed that lower disease activity at baseline contributed the achievement of DAS-low disease activity(odds ratio= 1.56, 95% confidence interval: 0.48-0.85). In the concomitant use of MTX or without MTX, the Δ values of DAS28-ESR from baseline to 24 months were -1.62, -1.13, respectively(P=0.12). And, the efficacy of patients after switching from tocilizumab(TCZ), which also inhibit IL-6 as same as JAK inhibitor, were not inferior as compared to non-switching from TCZ (Δ DAS28-ESR;-1.07, -1.61, respectively P=0.10).

Table 2.Univariate ModelMultivariate ModelOR(95% CI)P-valueOR(95% CI)P-valueAge(per 1-year increase)0.92(0.88-0.95)<0.001*0.91(0.87-0.95)<0.001*Disease duration(per 1-year increase)0.97(0.97-1.02)0.21Concomitant MTX use (yes/no)0.95(0.39-2.31)0.91Concomitant oral steroid use (yes/no)1.84(0.76-4.42)0.161.61(0.60-4.34)0.349Number of previous use of bDMARDs (per drug)1.26(0.99-1.62)0.051.39(1.05-1.84)0.02*DAS-ESR at baseline(per 1 increase)1.02(0.76-1.36)0.92LDA achievement at 1 year (yes/no)0.56(0.76-1.49)0.23RF positive (yes/no)0.91(0.32-2.56)0.85ACPA positive (yes/no)0.76(0.27-2.18)0.62

ORodds raio,95% CI95% confidence interval,MTXmethotrexate,bDMARDsbiologic disease-modifying antirheumatic drugs,ACPAanti-citrullinated protein antibodies,RFrheumatoid factor *P<0.05

Conclusion:

Our present study suggests that tofacitinib is effective in real-world settings even without concomitant MTX. Our results also suggest that for continuous use of tofacitinib without lack of efficacy, use tofacitinib earlier during switching strategy for RA patients who have failed to be treated with bDMARDs is better.

Disclosure of Interests:

None declared

Investigating global gene expression changes in a murine model of cherubism

Cherubism is a rare genetic disorder caused primarily by mutations in SH3BP2 resulting in excessive bone resorption and fibrous tissue overgrowth in the lower portions of the face. Bone marrow derived cell cultures derived from a murine model of cherubism display poor osteogenesis and spontaneous osteoclast formation. To develop a deeper understanding for the potential underlying mechanisms contributing to these phenotypes in mice, we compared global gene expression changes in hematopoietic and mesenchymal cell populations between cherubism and wild type mice. In the hematopoietic population, not surprisingly, upregulated genes were significantly enriched for functions related to osteoclastogenesis. However, these upregulated genes were also significantly enriched for functions associated with inflammation including arachidonic acid/prostaglandin signaling, regulators of coagulation and autoinflammation, extracellular matrix remodeling, and chemokine expression. In the mesenchymal population, we observed down regulation of osteoblast and adventitial reticular cell marker genes. Regulators of BMP and Wnt pathway associated genes showed numerous changes in gene expression, likely implicating the down regulation of BMP signaling and possibly the activation of certain Wnt pathways. Analyses of the cherubism derived mesenchymal population also revealed interesting changes in gene expression related to inflammation including the expression of distinct granzymes, chemokines, and sulfotransferases. These studies reveal complex changes in gene expression elicited from a cherubic mutation in Sh3bp2 that are informative to the mechanisms responding to inflammatory stimuli and repressing osteogenesis. The outcomes of this work are likely to have relevance not only to cherubism, but other inflammatory conditions impacting the skeleton.

FRI0098 ASSOCIATION BETWEEN THE SEROLOGIC STATUS OF ISOTYPE-SPECIFIC AUTOANTIBODIES AND THERAPEUTIC EFFICACY IN RHEUMATOID ARTHRITIS PATIENTS TREATED WITH ABATACEPT: A PROSPECTIVE ULTRASOUND COHORT STUDY IN JAPAN

Background:

The presence of anti-cyclic citrullinated protein antibodies (ACPA) and anti-carbamylated protein (anti-CarP) antibody is specific for rheumatoid arthritis (RA). Recently, it was reported that the serological status of ACPA is associated with the therapeutic response of the T-cell co-stimulation blocker abatacept (1, 2). However, it is currently unclear whether the serological status of each isotype levels of these autoantibodies before treatment introduction or the changes during treatment are associated with the therapeutic response of abatacept.

Objectives:

To evaluate longitudinal changes in the isotypes of ACPA and anti-CarP in RA patients treated with abatacept, and associations between the baseline serological status/ these changes and clinical response/ ultrasonographic response.

Methods:

This study is part of an ongoing non-randomized multicenter prospective cohort study of patients with active RA who received biological or targeted DMARD therapy at 13 participating rheumatology centers from the Kyushu region of Japan since June 2013 (3). As of the present report, we enrolled 43 consecutive Japanese patients with active RA who have introduced treatment with abatacept and had finished the first 12-month observation period. We evaluated disease activity by clinical composite measure and ultrasound score at baseline, 3, 6, 9 and 12 months. In ultrasound of bilateral hands from 22 sites, the findings obtained by gray-scale (GS) and power Doppler (PD) assessments were graded on a semi-quantitative scale from 0 to 3 and the sum of GS or PD scores was used as the total GS or PD score. The serum levels of IgG/IgM/IgA-type of ACPA and anti-CarP were measured by the ELISA method in Leiden University Medical Center. We evaluated the association between serologic status of autoantibodies and clinical /ultrasonographic therapeutic efficacy.

Results:

The median age was 72 years, and the disease duration was 54 months. Methotrexate was concomitant in 22 (51%). Sixteen (37%) patients had a history of previous use of biological DMARDs. Nineteen (44%) and 23 (54%) patients achieved SDAI remission and PD remission (total PD score =0) at 12 months, respectively. The serum levels of all isotypes of ACPA/anti-CarP significantly decreased at 12 months from baseline. The reduction of IgM-ACPA level significantly correlated with the reduction of SDAI (rs=0.33, p=0.031) and total PD score (rs=0.49, p=0.0007). Both clinical and ultrasonographic therapeutic responses were better in patients with the detectable IgM-ACPA at baseline than in patients without that (Figure): the reduction of SDAI (p=0.0078) and that of total PD score (p=0.0079) were significantly larger in the former than in the latter. All isotype of anti-CarP did not associate with therapeutic response.

Conclusion:

Treatment of abatacept induced to the reduction of the autoantibody levels. The IgM-ACPA level at baseline and the change in IgM-ACPA associated with both clinical and ultrasonographic therapeutic response in patients treated with abatacept. IgM-ACPA, compared with usual IgG-ACPA, better reflects the treatment response of abatcept in patients with RA

References:

[1]Ann Rheum Dis. 2016;75:709, 2) RMD Open. 2018;4:e000564, 3)Arthritis Care Res (Hoboken). 2018;70:1719.

Acknowledgments:

We have acknowledged for all the members of Kyushu multicenter rheumatoid arthritis ultrasound prospective observational cohort study group.

Disclosure of Interests:

Shin-ya Kawashiri Grant/research support from: This work was supported by Bristol-Myers Squibb and Ono Pharmaceutical. co., Yushiro Endo: None declared, Ayako Nishino: None declared, Toshimasa Shimizu: None declared, Yukitaka Ueki: None declared, Nobutaka Eiraku: None declared, Akitomo Okada: None declared, Naoki Matsuoka: None declared, Tamami Yoshitama: None declared, Hideki Nakamura: None declared, Mami Tamai: None declared, Tomoki Origuchi: None declared, Rene Toes: None declared, Thomas Huizinga Grant/research support from: Ablynx, Bristol-Myers Squibb, Roche, Sanofi, Consultant of: Ablynx, Bristol-Myers Squibb, Roche, Sanofi, Atsushi Kawakami: None declared

RANKL-independent osteoclastogenesis in the SH3BP2 cherubism mice

Even though the receptor activator of the nuclear factor-κB ligand (RANKL) and its receptor RANK have an exclusive role in osteoclastogenesis, the possibility of RANKL/RANK-independent osteoclastogenesis has been the subject of a long-standing debate in bone biology. In contrast, it has been reported that calvarial injection of TNF-ɑ elicits significant osteoclastogenesis in the absence of RANKL/RANK in NF-κB2- and RBP-J-deficient mice, suggesting that inflammatory challenges and secondary gene manipulation are the prerequisites for RANKL/RANK-deficient mice to develop osteoclasts in vivo. Here we report that, even in the absence of RANKL (Rankl^−/−), cherubism mice (Sh3bp2^KI/KI) harboring the homozygous gain-of-function mutation in SH3-domain binding protein 2 (SH3BP2) develop tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts spontaneously. The Sh3bp2^KI/KIRankl^−/− mice exhibit an increase in tooth exposure and a decrease in bone volume/total volume compared to Sh3bp2^+/+Rankl^−/− mice. The multinucleated cells were stained positively for cathepsin K. Osteoclastic marker gene expression in bone and serum TRAP5b levels were elevated in Sh3bp2^KI/KIRankl^−/− mice. Elevation of the serum TNF-ɑ levels suggested that TNF-ɑ is a driver for the RANKL-independent osteoclast formation in Sh3bp2^KI/KI mice. Our results provide a novel mutant model that develops osteoclasts independent of RANKL and establish that the gain-of-function of SH3BP2 promotes osteoclastogenesis not only in the presence of RANKL but also in the absence of RANKL.

•

Cherubism mutation improves osteopetrosis in RANKL-deficient mice.

•

RANKL-deficient cherubism mice develop functional osteoclasts.

•

Gain-of-function of SH3BP2 and TNF-ɑ are involved in the mechanism of RANKL-independent osteoclastogenesis.

Alveolar Bone Protection by Targeting the SH3BP2-SYK Axis in Osteoclasts

Periodontitis is a bacterially induced chronic inflammatory condition of the oral cavity where tooth-supporting tissues including alveolar bone are destructed. Previously, we have shown that the adaptor protein SH3-domain binding protein 2 (SH3BP2) plays a critical role in inflammatory response and osteoclastogenesis of myeloid lineage cells through spleen tyrosine kinase (SYK). In this study, we show that SH3BP2 is a novel regulator for alveolar bone resorption in periodontitis. Micro-CT analysis of SH3BP2-deficient (Sh3bp2 ^-/- ) mice challenged with ligature-induced periodontitis revealed that Sh3bp2 ^-/- mice develop decreased alveolar bone loss (male 14.9% ± 10.2%; female 19.0% ± 6.0%) compared with wild-type control mice (male 25.3% ± 5.8%; female 30.8% ± 5.8%). Lack of SH3BP2 did not change the inflammatory cytokine expression and osteoclast induction. Conditional knockout of SH3BP2 and SYK in myeloid lineage cells with LysM-Cre mice recapitulated the reduced bone loss without affecting both inflammatory cytokine expression and osteoclast induction, suggesting that the SH3BP2-SYK axis plays a key role in regulating alveolar bone loss by mechanisms that regulate the bone-resorbing function of osteoclasts rather than differentiation. Administration of a new SYK inhibitor GS-9973 before or after periodontitis induction reduced bone resorption without affecting inflammatory reaction in gingival tissues. In vitro, GS-9973 treatment of bone marrow-derived M-CSF-dependent macrophages suppressed tartrate-resistant acid phosphatase (TRAP)-positive osteoclast formation with decreased mineral resorption capacity even when GS-9973 was added after RANKL stimulation. Thus, the data suggest that SH3BP2-SYK is a novel signaling axis for regulating alveolar bone loss in periodontitis and that SYK can be a potential therapeutic target to suppress alveolar bone resorption in periodontal diseases. © 2019 American Society for Bone and Mineral Research. © 2019 American Society for Bone and Mineral Research.

P5500Acute coronary syndrome in young patients: frequency, mechanisms and clinical outcomes following percutaneous coronary intervention

Introduction

Acute coronary syndromes (ACS) mainly affect older patients and little is known on the frequency, the underlying causes and outcomes following ACS in young.

Purpose

To investigate the frequency, mechanisms and clinical outcomes of young patients suffering from ACS and undergoing percutaneous coronary intervention (PCI).

Methods

Between February 2009 and December 2016, 6720 consecutive patients undergoing PCI for an ACS were prospectively enrolled. We defined young patients as male <45 years or female <50 years. The primary endpoint was the patient-oriented composite endpoint (POCE) defined as the composite of all-cause death, myocardial infarction or any revascularization at 12 months. The mechanisms of ACS in young patients (atherosclerotic vs. embolic vs. spontaneous coronary artery dissection) were retrospectively assessed by an adjudication committee based on clinical and angiographic criteria.

Results

Among 6720 ACS patients, 378 (5.6%) patients were young (41±5 years, 73% male). Young patients, as compared to old patients, presented more frequently with STEMI (64% vs. 45%; p<0.001) and single vessel disease (85% vs. 74%; p<0.001). Cardiovascular risk factors were more frequent in young patients including BMI>30 kg/m2 (34% vs. 22%; p<0.001), smoking (68% vs. 31%; p<0.001), positive family history of coronary artery disease (35% vs. 23%; p<0.001) and baseline LDL-C levels (3.3±1.1 mmol/l vs. 2.9±1.1 mmol/l; p<0.001). Diabetes mellitus was less frequent in the young patient group (10% vs. 21%; p<0.001). The mechanisms of ACS in young patients were atherosclerotic in 87%, coronary embolism in 9%, and spontaneous coronary artery dissection in 4%. At 12 months, the primary endpoint POCE occurred less frequently in young patients (9.3% vs. 17%; HR 0.52, 95% CI 0.37–0.73; p<0.001). The rates of the individual components of the primary endpoint were lower in young patients including all-cause death (3.4% vs. 9.4%; HR 0.36, 95% CI 0.21–0.62; p<0.001), myocardial infarction (1.9% vs. 3.7%; HR 0.48, 95% CI 0.22–1.01; p=0.053) and any revascularization (5.6% vs. 7.7%; HR 0.68, 95% CI 0.44–1.05; p=0.083). Young patients with coronary embolism or spontaneous coronary artery dissection had a higher rate of cardiac death at 12 months as compared to young patients with atherosclerotic disease (embolic vs. atherosclerotic: 9.4% vs. 2.2%; HR 4.3, 95% CI 1.11–16.71; p=0.02; spontaneous coronary artery dissection vs. atherosclerotic: 17.6% vs. 2.2%; HR 8.1, 95% CI 2.1–31.1; p<0.001).

Conclusions

Approximately one out of 20 ACS patients undergoing PCI was young and the main presumed mechanism of ACS was atherosclerosis (87%) followed by coronary embolism (9%) and spontaneous coronary artery dissection (4%). While young ACS patients carry a lower risk for future cardiovascular events as compared with older patients, the high cardiac death rates following embolic disease or spontaneous coronary artery dissections deserves particular attention.

122Mechanism and impact of lesion morphology on the late lumen loss of drug-eluting resorbable magnesium scaffolds: a serial optical coherence tomography study

Introduction

Resorbable Magnesium Scaffolds have demonstrated favourable clinical results with acceptable late lumen loss (LLL). However, the pathomechanisms influencing LLL of resorbable sirolimus-eluting metallic scaffold (Magmaris) have not been analyzed.

Purpose

Using serial optical coherence tomography (OCT), we investigated potential factors, i.e. the contribution of recoil versus neointimal hyperplasia (NIH).

Methods

Patients who were enrolled into BIOSOLVE-II, and underwent serial angiography and OCT (baseline and follow-up: 6-month and/or 1-year) were analyzed. Patients were divided into 2 groups based on angiographic in-scaffold LLL <0.5mm or ≥0.5mm. Endpoints were late absolute recoil and NIH area as assessed by OCT.

Results

A total of 70 patients (LLL <0.5mm: n=41, LLL ≥0.5mm: n=29) were serially analyzed. Patient and lesion characteristics were comparable and there was no significant difference in mean and minimal scaffold area between groups at baseline. Late absolute recoil was significantly smaller among patients with LLL <0.5mm (0.53±0.68 mm2) compared with those with LLL ≥0.5mm (1.48±1.20 mm2, P<0.001) (Figure). A small difference in NIH area at follow-up was observed (LLL <0.5mm: 1.47±0.33 mm2 vs. LLL ≥0.5mm: 1.68±0.34 mm2, P=0.013). In a matched-frame analysis (baseline and follow-up), late absolute recoil varied according to the underlying plaque type (lipid: 0.63±1.23 mm2, calcified: 0.81±1.44 mm2, and fibrous: 1.20±1.52 mm2, P<0.001), while there was no difference with regards to NIH area (P=0.132).

Conclusion

The main driver of late lumen loss of sirolimus-eluting absorbable metal scaffold was late scaffold recoil, while the contribution of NIH was modest. The degree of late scaffold recoil depended on the underlying plaque type and was highest among fibrotic lesions. Future studies will address the impact of procedural factors such as adequate lesion preparation and post-dilatation.

Acknowledgement/Funding

Biotronik

Epigenetic regulation of NfatC1 transcription and osteoclastogenesis by nicotinamide phosphoribosyl transferase in the pathogenesis of arthritis

Nicotinamide phosphoribosyltransferase (NAMPT) functions in NAD synthesis, apoptosis, and inflammation. Dysregulation of NAMPT has been associated with several inflammatory diseases, including rheumatoid arthritis (RA). The purpose of this study was to investigate NAMPT’s role in arthritis using mouse and cellular models. Collagen-induced arthritis (CIA) in DBA/1J Nampt^+/− mice was evaluated by ELISA, micro-CT, and RNA-sequencing (RNA-seq). In vitro Nampt loss-of-function and gain-of-function studies on osteoclastogenesis were examined by TRAP staining, nascent RNA capture, luciferase reporter assays, and ChIP-PCR. Nampt-deficient mice presented with suppressed inflammatory bone destruction and disease progression in a CIA mouse model. Nampt expression was required for the epigenetic regulation of the Nfatc1 promoter and osteoclastogenesis. Finally, RNA-seq identified 690 differentially expressed genes in whole ankle joints which associated (P < 0.05) with Nampt expression and CIA. Selected target was validated by RT-PCR or functional characterization. We have provided evidence that NAMPT functions as a genetic risk factor and a potential therapeutic target to RA.

Second-Generation SYK Inhibitor Entospletinib Ameliorates Fully Established Inflammation and Bone Destruction in the Cherubism Mouse Model

Cherubism is a craniofacial disorder characterized by maxillary and mandibular bone destruction. Gain-of-function mutations in the SH3-domain binding protein 2 (SH3BP2) are responsible for the excessive bone resorption caused by fibrous inflammatory lesions. A homozygous knock-in (KI) mouse model for cherubism (Sh3bp2^KI/KI ) develops autoinflammation resulting in systemic bone destruction. Although administration of the TNF-α blocker etanercept to neonatal Sh3bp2^KI/KI mice prevented the disease onset, this therapy was not effective for adult Sh3bp2^KI/KI mice or human cherubism patients who already had lesions. Because genetic ablation of spleen tyrosine kinase (SYK) in myeloid cells rescues Sh3bp2^KI/KI mice from inflammation, we examined whether SYK inhibitor administration can improve fully developed cherubism symptoms in adult Sh3bp2^KI/KI mice. Entospletinib (GS-9973) was intraperitoneally injected into 10-week-old Sh3bp2^KI/KI mice every day for 6 weeks. Treatment with GS-9973 improved facial swelling and histomorphometric analysis of lung and liver tissue showed that GS-9973 administration significantly reduced inflammatory infiltrates associated with decreased levels of serum TNF-α. Micro-computed tomography (μCT) analysis showed that GS-9973 treatment reduced bone erosion in mandibles, calvariae, and ankle and elbow joints of Sh3bp2^KI/KI mice compared to Sh3bp2^KI/KI mice treated with dimethyl sulfoxide (DMSO). Taken together, the results demonstrate that administration of the SYK inhibitor ameliorates an already established cherubism phenotype in mice, suggesting that pharmacological inhibition of SYK may be a treatment option for cherubism patients with active disease progression. © 2018 American Society for Bone and Mineral Research.

Mouse Cre Models for the Study of Bone Diseases

PURPOSE

Transgenic Cre lines are a valuable tool for conditionally inactivating or activating genes to understand their function. Here, we provide an overview of Cre transgenic models used for studying gene function in bone cells and discuss their advantages and limitations, with particular emphasis on Cre lines used for studying osteocyte and osteoclast function.

RECENT FINDINGS

Recent studies have shown that many bone cell-targeted Cre models are not as specific as originally thought. To ensure accurate data interpretation, it is important for investigators to test for unexpected recombination events due to transient expression of Cre recombinase during development or in precursor cells and to be aware of the potential for germ line recombination of targeted genes as well as the potential for unexpected phenotypes due to the Cre transgene. Although many of the bone-targeted Cre-deleter strains are imperfect and each model has its own limitations, their careful use will continue to provide key advances in our understanding of bone cell function in health and disease.

Rescue of a cherubism bone marrow stromal culture phenotype by reducing TGFβ signaling

We utilized a bone marrow stromal culture system to investigate changes in TGFβ signaling in a mouse model for cherubism (Sh3bp2^KI/KI). Interestingly, bone marrow cultures derived from cherubism mice not only displayed impaired osteoblast differentiation, but also had spontaneous osteoclast formation. PAI1, a target gene of TGFβ signaling, was elevated 2-fold in cherubism CD11b^-,CD45^- cells compared to wild type cells, while the expression of BAMBI, an inhibitor of TGFβ signaling, was down-regulated. We also discovered that treatment of cherubism cultures with antagonists of the TGFβ signaling pathway could largely rescue osteoblast differentiation and markedly reduce spontaneous osteoclast formation. Treatment with the type I TGFβ receptor small molecule inhibitor SB505124 increased osteoblast reporter gene Col1a1-2.3 expression 24-fold and increased the expression of osteoblast gene markers Osterix (Sp7) 25-fold, Bone Sialoprotein (BSP) 7-fold, Osteocalcin (Bglap1) 100-fold, and Dentin Matrix Protein 1 (DMP1) 35-fold. In contrast, SB505124 treatment resulted in a significant reductions in osteoclast number and size. Gene expression analyses for RANKL, a positive regulator of osteoclast formation was 2.5-fold higher in osteoblast cultures derived from Sh3bp2^KI/KI mice compared to wild type cultures, whereas OPG, an inhibitor of RANKL was 5-fold lower. However, SB505124 treatment reduced RANKL almost back down to wild type levels, while increasing OPG expression. Our studies also implicate a role for TGFβ ligands in the etiology of cherubism. Blocking of TGFβ ligands with the monoclonal antibody 1D11 increased Col1a1-2.3 reporter expression 4-fold and 13-fold in cultures derived from Sh3bp2^KI/+ and Sh3bp2^KI/KI mice, respectively. Serum levels of latent TGFβ1 were also 2-fold higher in SH3BP2^KI/KI mice compared to wild type littermates. Taken together, these studies provide evidence that elevated levels of TGFβ signaling may contribute to the disease phenotype of cherubism and a reduction in pathway activity may be an effective therapeutic approach to treat this rare disease.

Pharmacological inhibition of tankyrase induces bone loss in mice by increasing osteoclastogenesis

Tankyrase is a poly (ADP-ribose) polymerase that leads to ubiquitination and degradation of target proteins. Since tankyrase inhibitors suppress the degradation of AXIN protein, a negative regulator of the canonical Wnt pathway, they effectively act as Wnt inhibitors. Small molecule tankyrase inhibitors are being investigated as drug candidates for cancer and fibrotic diseases, in which the Wnt pathways are aberrantly activated. Tankyrase is also reported to degrade the adaptor protein SH3BP2 (SH3 domain-binding protein 2). We have previously shown that SH3BP2 gain-of-function mutation enhances receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in murine bone marrow-derived macrophages (BMMs). Although the interaction between tankyrase and SH3BP2 has been reported, it is not clear whether and how the inhibition of tankyrase affects bone cells and bone mass. Here, we have demonstrated that tankyrase inhibitors (IWR-1, XAV939, and G007-LK) enhanced RANKL-induced osteoclast formation and function in murine BMMs and human peripheral blood mononuclear cells through the accumulation of SH3BP2, subsequent phosphorylation of SYK, and nuclear translocation of NFATc1. Tankyrase inhibitors also enhanced osteoblast differentiation and maturation, represented by increased expression of osteoblast-associated genes accompanied by the accumulation of SH3BP2 protein and enhanced nuclear translocation of ABL, TAZ, and Runx2 in primary osteoblasts. Most importantly, pharmacological inhibition of tankyrase in mice significantly decreased tibia and lumbar vertebrae bone volumes in association with increased numbers of osteoclasts. Our findings uncover the role of tankyrase inhibition in bone cells and highlight the potential adverse effects of the inhibitor on bone.

Cherubism Mice Also Deficient in c-Fos Exhibit Inflammatory Bone Destruction Executed by Macrophages That Express MMP14 Despite the Absence of TRAP+ Osteoclasts

Currently, it is believed that osteoclasts positive for tartrate-resistant acid phosphatase (TRAP+) are the exclusive bone-resorbing cells responsible for focal bone destruction in inflammatory arthritis. Recently, a mouse model of cherubism (Sh3bp2^KI/KI ) with a homozygous gain-of-function mutation in the SH3-domain binding protein 2 (SH3BP2) was shown to develop auto-inflammatory joint destruction. Here, we demonstrate that Sh3bp2^KI/KI mice also deficient in the FBJ osteosarcoma oncogene (c-Fos) still exhibit noticeable bone erosion at the distal tibia even in the absence of osteoclasts at 12 weeks old. Levels of serum collagen I C-terminal telopeptide (ICTP), a marker of bone resorption generated by matrix metalloproteinases (MMPs), were elevated, whereas levels of serum cross-linked C-telopeptide (CTX), another resorption marker produced by cathepsin K, were not increased. Collagenolytic MMP levels were increased in the inflamed joints of the Sh3bp2^KI/KI mice deficient in c-Fos. Resorption pits contained a large number of F4/80+ macrophages and genetic depletion of macrophages rescued these erosive changes. Importantly, administration of NSC405020, an MMP14 inhibitor targeted to the hemopexin (PEX) domain, suppressed bone erosion in c-Fos-deficient Sh3bp2^KI/KI mice. After activation of the NF-κB pathway, macrophage colony-stimulating factor (M-CSF)-dependent macrophages from c-Fos-deficient Sh3bp2^KI/KI mice expressed increased amounts of MMP14 compared with wild-type macrophages. Interestingly, receptor activator of NF-κB ligand (RANKL)-deficient Sh3bp2^KI/KI mice failed to show notable bone erosion, whereas c-Fos deletion did restore bone erosion to the RANKL-deficient Sh3bp2^KI/KI mice, suggesting that osteolytic transformation of macrophages requires both loss-of-function of c-Fos and gain-of-function of SH3BP2 in this model. These data provide the first genetic evidence that cells other than osteoclasts can cause focal bone destruction in inflammatory bone disease and suggest that MMP14 is a key mediator conferring pathological bone-resorbing capacity on c-Fos-deficient Sh3bp2^KI/KI macrophages. In summary, the paradigm that osteoclasts are the exclusive cells executing inflammatory bone destruction may need to be reevaluated based on our findings with c-Fos-deficient cherubism mice lacking osteoclasts. © 2017 American Society for Bone and Mineral Research.