Risks and benefits of sharing patient information on social media: a digital dilemma

Social media (SoMe) has witnessed remarkable growth and emerged as a dominant method of communication worldwide. Platforms such as Facebook, X (formerly Twitter), LinkedIn, Instagram, TikTok, and YouTube have become important tools of the digital native generation. In the field of medicine, particularly, cardiology, attitudes towards SoMe have shifted, and professionals increasingly utilize it to share scientific findings, network with experts, and enhance teaching and learning. Notably, SoMe is being leveraged for teaching purposes, including the sharing of challenging and intriguing cases. However, sharing patient data, including photos or images, online carries significant implications and risks, potentially compromising individual privacy both online and offline. Privacy and data protection are fundamental rights within European Union treaties, and the General Data Protection Regulation (GDPR) serves as the cornerstone of data protection legislation. The GDPR outlines crucial requirements, such as obtaining 'consent' and implementing 'anonymization', that must be met before sharing sensitive and patient-identifiable information. Additionally, it is vital to consider the patient's perspective and prioritize ethical and social considerations when addressing challenges associated with sharing patient information on SoMe platforms. Given the absence of a peer-review process and clear guidelines, we present an initial approach, a code of conduct, and recommendations for the ethical use of SoMe. In conclusion, this comprehensive review underscores the importance of a balanced approach that ensures patient privacy and upholds ethical standards while harnessing the immense potential of SoMe to advance cardiology practice and facilitate knowledge dissemination.

Molecular basis of proton-sensing by G protein-coupled receptors

Three proton-sensing G protein-coupled receptors (GPCRs), GPR4, GPR65, and GPR68, respond to changes in extracellular pH to regulate diverse physiology and are implicated in a wide range of diseases. A central challenge in determining how protons activate these receptors is identifying the set of residues that bind protons. Here, we determine structures of each receptor to understand the spatial arrangement of putative proton sensing residues in the active state. With a newly developed deep mutational scanning approach, we determined the functional importance of every residue in proton activation for GPR68 by generating ~9,500 mutants and measuring effects on signaling and surface expression. This unbiased screen revealed that, unlike other proton-sensitive cell surface channels and receptors, no single site is critical for proton recognition in GPR68. Instead, a network of titratable residues extend from the extracellular surface to the transmembrane region and converge on canonical class A GPCR activation motifs to activate proton-sensing GPCRs. More broadly, our approach integrating structure and unbiased functional interrogation defines a new framework for understanding the rich complexity of GPCR signaling.

GPR161 structure uncovers the redundant role of sterol-regulated ciliary cAMP signaling in the Hedgehog pathway

The orphan G protein-coupled receptor (GPCR) GPR161 plays a central role in development by suppressing Hedgehog signaling. The fundamental basis of how GPR161 is activated remains unclear. Here, we determined a cryogenic-electron microscopy structure of active human GPR161 bound to heterotrimeric Gs. This structure revealed an extracellular loop 2 that occupies the canonical GPCR orthosteric ligand pocket. Furthermore, a sterol that binds adjacent to transmembrane helices 6 and 7 stabilizes a GPR161 conformation required for Gs coupling. Mutations that prevent sterol binding to GPR161 suppress Gs-mediated signaling. These mutants retain the ability to suppress GLI2 transcription factor accumulation in primary cilia, a key function of ciliary GPR161. By contrast, a protein kinase A-binding site in the GPR161 C terminus is critical in suppressing GLI2 ciliary accumulation. Our work highlights how structural features of GPR161 interface with the Hedgehog pathway and sets a foundation to understand the role of GPR161 function in other signaling pathways.

GPR161 structure uncovers the redundant role of sterol-regulated ciliary cAMP signaling in the Hedgehog pathway

The orphan G protein-coupled receptor (GPCR) GPR161 is enriched in primary cilia, where it plays a central role in suppressing Hedgehog signaling1. GPR161 mutations lead to developmental defects and cancers2,3,4. The fundamental basis of how GPR161 is activated, including potential endogenous activators and pathway-relevant signal transducers, remains unclear. To elucidate GPR161 function, we determined a cryogenic-electron microscopy structure of active GPR161 bound to the heterotrimeric G protein complex Gs. This structure revealed an extracellular loop 2 that occupies the canonical GPCR orthosteric ligand pocket. Furthermore, we identify a sterol that binds to a conserved extrahelical site adjacent to transmembrane helices 6 and 7 and stabilizes a GPR161 conformation required for Gs coupling. Mutations that prevent sterol binding to GPR161 suppress cAMP pathway activation. Surprisingly, these mutants retain the ability to suppress GLI2 transcription factor accumulation in cilia, a key function of ciliary GPR161 in Hedgehog pathway suppression. By contrast, a protein kinase A-binding site in the GPR161 C-terminus is critical in suppressing GLI2 ciliary accumulation. Our work highlights how unique structural features of GPR161 interface with the Hedgehog pathway and sets a foundation to understand the broader role of GPR161 function in other signaling pathways.

Autoantibody mimicry of hormone action at the thyrotropin receptor

Thyroid hormones are vital in metabolism, growth and development1. Thyroid hormone synthesis is controlled by thyrotropin (TSH), which acts at the thyrotropin receptor (TSHR)2. In patients with Graves' disease, autoantibodies that activate the TSHR pathologically increase thyroid hormone activity3. How autoantibodies mimic thyrotropin function remains unclear. Here we determined cryo-electron microscopy structures of active and inactive TSHR. In inactive TSHR, the extracellular domain lies close to the membrane bilayer. Thyrotropin selects an upright orientation of the extracellular domain owing to steric clashes between a conserved hormone glycan and the membrane bilayer. An activating autoantibody from a patient with Graves' disease selects a similar upright orientation of the extracellular domain. Reorientation of the extracellular domain transduces a conformational change in the seven-transmembrane-segment domain via a conserved hinge domain, a tethered peptide agonist and a phospholipid that binds within the seven-transmembrane-segment domain. Rotation of the TSHR extracellular domain relative to the membrane bilayer is sufficient for receptor activation, revealing a shared mechanism for other glycoprotein hormone receptors that may also extend to other G-protein-coupled receptors with large extracellular domains.

Fusion protein strategies for cryo-EM study of G protein-coupled receptors

Single particle cryogenic-electron microscopy (cryo-EM) is used extensively to determine structures of activated G protein-coupled receptors (GPCRs) in complex with G proteins or arrestins. However, applying it to GPCRs without signaling proteins remains challenging because most receptors lack structural features in their soluble domains to facilitate image alignment. In GPCR crystallography, inserting a fusion protein between transmembrane helices 5 and 6 is a highly successful strategy for crystallization. Although a similar strategy has the potential to broadly facilitate cryo-EM structure determination of GPCRs alone without signaling protein, the critical determinants that make this approach successful are not yet clear. Here, we address this shortcoming by exploring different fusion protein designs, which lead to structures of antagonist bound A2A adenosine receptor at 3.4 Å resolution and unliganded Smoothened at 3.7 Å resolution. The fusion strategies explored here are likely applicable to cryo-EM interrogation of other GPCRs and small integral membrane proteins.

Knockout of purinergic receptor Y13 (P2Y13) results in an improved outcome of metabolic syndrome in mice

 

Metabolic syndrome (MetS) clusters the main risk factors for cardiovascular diseases (CVDs) and endocrine dysfunction. The pathomechanism of MetS is described as local death of hypertrophic adipocytes releasing danger-associated molecular patterns (DAMPs) such as nucleotides (e.g. ADP). This promotes a long term inflammation of adipose tissue via activation of purinergic receptors with a gradual shift towards a pro-inflammatory environment. The ADP receptor P2Y13 is both described in metabolic and immunological processes. These combined characteristics make the P2Y13 an interesting candidate to investigate its role in MetS. Nevertheless, the role of P2Y13R in the pathogenesis of MetS is currently unknown and shall be analyzed in this study.

BMDM isolation and differentiation to Mϕ using M-CSF and subsequent stimulation with medium, LPS and IFNγ or IL4; Expression was quantified using Taqman. Male C57Bl6/J wild-type (WT) and P2Y13-deficient (KO) mice were fed a HFD for 20 weeks; body weight and food consumption were recorded weekly. GTT, ITT and metabolic cages were performed after 15 weeks with euthanization after 20 weeks. In order to distinguish the effect of hematopoetic or somatic cells, mice were lethally irradiated with 9.4Gy and reconstituted with donor bone-marrow (BM) via tail vein injection.

We observed a unique expression of P2Y13R on pro-inflammatory M1 Mϕ. After HFD feeding KO mice showed higher O2 consumption compared to WT mice (AUC of O2 consumption on 2nd day= KO:61620±2261mL/kg vs WT: 53830±916mL/kg, p<0.05). Although KO mice consumed more food compared to WT littermates (KO:5.7±0.5g/d vs WT:3.1±0.1g/d, p<0.0001), they showed significantly decelerated weight gain (e.g.week 15→KO:147,292±5,26% vs WT:180.8±15.9%, p<0.05). Obese KO animals outperformed obese WT littermates in a peritoneal glucose tolerance test (GTT) (2h post-injection (post-i.) →KO:273.7±46.3mg/dL vs WT: 555.0±40.8mg/dL, p<0.05). KO mice on HFD were protected from developing a fatty liver. HFD KO mice receiving WT BM show accelerated weight gain compared to KO mice receiving KO BM (e.g.week 10 WT in KO: 111.2±2.2% vs KO in KO: 102.2±1.2%, p<0.05). In the GTT irradiated KO mice either receiving KO or WT BM are protected from HFD induced impaired glucose homeostasis (45min post-i.; KO→KO:222.1±21.2mg/dL vs WT→KO:232.8±15.9mg/dL vs WT on chow diet:240.4±18.6mg/dL). Contrary, WT mice receiving KO or WT BM developed a glucose resistance comparable to non-irradiated WT mice (45min post-i.; WT→WT:423.8±61.7mg/dL vs KO→WT:434.3±51.1 vs WT on HFD:574.4±7.9).

P2Y13 KO improves the outcome of MetS in mice with improved glucose homeostasis, decelerated weight gain, no fatty liver development and better metabolic turnover. BM transplantation experiments suggest a somatic component as possible explanation of these observations. Given these beneficial metabolic effects, we hypothesize that antagonization of P2Y13R could be a promising therapeutic tool in the field of MetS.

Funding Acknowledgement

Type of funding source: None

Macrophage-specific IRF5 deficiency stabilizes atherosclerotic plaques in ApoE−/− mice

Background

Interferon regulatory factor (IRF) 5 is a transcription factor promoting inflammatory macrophage polarization (M1 type). Given the central role of macrophages in atherosclerotic plaque development we hypothesized that macrophage specific deletion of IRF5 will protect from atherosclerosis.

Purpose

Investigate whether intrinsic blockade of M1 macrophage polarization ameliorates atherosclerosis

Methods

Female ApoE−/−LysMCre/wtIRF5flox/floxand ApoE−/−LysMwt/wtIRF5flox/floxmice were fed a high cholesterol diet for 3 months, and atherosclerotic plaque size and compositions as well as inflammatory gene expression were analyzed. Mechanistically, IRF5-dependend bone marrow derived macrophage cytokine profiles were tested under M1 and M2 polarizing conditions. Aortic macrophage chimerism in irradiated ApoE−/− mice reconstituted with a mixture of CD45.1+ ApoE−/− (WT) and CD45.2+ ApoE−/− LysMCre/WtIRF5flox/flox(KO) bone marrow was evaluated to distinguish systemic from intra-plaque effects on monocyte/macrophage kinetics.

Results

Macrophage-specific IRF5 deficiency blunted LPS/IFNg-induced IL-1β and TNFα gene expression in vitro. In ApoE−/− mice, macrophage-specific IRF5 deficiency did not alter lesion size in the aortic root but significantly reduced macrophage and lipid contents by about 25% while increasing collagen deposition by over 30%. This was accompanied by relative reductions in gene expressions of pro-inflammatory (IL-1β, IL-6, IL-12) and increases in anti-inflammatory (Mertk, TGFβ, CD206) markers in atherosclerotic aortas of ApoE−/−LysMCre/wtIRF5flox/floxmice. When competing with IRF5 deficient cells in mixed irradiation bone marrow chimeras, IRF5 competent macrophages showed an advantage in accumulating in atherosclerotic aortas as disease progressed independent of monocyte recruitment.

Conclusion

Transcription factor IRF5 promotes a pro-inflammatory response in macrophages leading to vulnerable plaque formation and plaque destabilization, providing genetic evidence for targeting macrophage polarization in atherosclerosis.

Funding Acknowledgement

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

Deficiency of the purinergic receptor P2X4 limits atherosclerosis in mice

Introduction

Extracellular nucleotides like ATP promote inflammation as danger signals in various chronic diseases via purinergic receptors. In our previous work we identified P2X4 expression in murine atherosclerotic lesions. Therefore, we hypothesized a contribution of the ATP-P2X4 axis to vascular inflammation in atherosclerosis.

Methods

To investigate the functional role of P2X4 in atherogenesis, wild-type LDL-receptor deficient mice (LDLR−/−) and P2X4-deficient LDLR−/− mice (P2X4−/−LDLR−/−) were fed a high cholesterol diet for 16 weeks. Plaque progression in aortic arches was monitored by echography at intervals of 4 weeks, and leukocyte subsets in blood samples were analysed by flow cytometry. Atherosclerotic lesions were then assessed histologically in aortic root, arch, and abdominal aorta. In order to assess leukocyte recruitment, intravital microscopy was performed after injection of ATP in P2X4−/− or wildtype mice (WT). Regarding transferability to human disease, atherosclerotic plaque from carotid endarterectomy has been stained immunohistochemically for P2X4-receptor expression.

Results

After 16 weeks, P2X4-deficient mice showed significantly reduced atherosclerotic lesions in the aortic root (n=40, LDLR−/−: 0.47 mm2, P2X4−/−LDLR−/−: 0.39 mm2, p=0.04). Ly6C- monocyte count in peripheral blood was higher in P2X4−/−LDLR−/− (n=32, LDLR−/−: 241/μl, P2X4−/−LDLR−/−: 542/μl, p=0.0088), shifting the balance to a more anti-inflammatory subset. Memory-cell generation of CD4-T-cells is significantly higher in knockout-mice, suggesting an involvement of T-helper cells (n=25, LDLR−/−: 27%, P2X4−/−LDLR−/−: 46%, p=0.0003). Peritoneally injected ATP induced leukocyte rolling in WT, but not in P2X4-deficient mice. In human carotid arteries, atherosclerotic plaque shows higher staining for P2X4−/− receptor than not diseased areas.

Conclusion

P2X4-deficiency enhances anti-inflammatory leukocytes in peripheral blood and reduces atherosclerosis. Therefore, blocking the ATP-P2X4 axis may prevent leukocyte recruitment to atherosclerotic lesions and could present a potential new target for anti-atherogenic therapy.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was supported by a research grant of the German Research Foundation (DFG) to Peter Stachon. Sebastian König was supported by a research grant of the German Cardiac Society (DGK)

P733Cholesterol uptake triggers macrophage proliferation in the plaque

Background

Guidelines recommend cholesterol lowering for primary and secondary prevention of cardiovascular disease. While lipid lowering has been reported to induce plaque regression, the underlying mechanisms have remained speculative.

Purpose

We hypothesize that lipid uptake triggers local macrophage proliferation in the plaque, and conversely, statin treatment inhibits local macrophage proliferation leading to plaque regression.

Methods

Mixed bone marrow chimeras were generated in LDLR−/− mice reconstituted with wild type and scavenger receptor deficient or cholesterol exporter deficient bone marrow cells to study cell autonomous effects on macrophage proliferation. APOE*3-Leiden.huCETP mice with established atherosclerosis were randomized to three groups: Continued cholesterol diet, cholesterol diet supplemented with 0.01% atorvastatin, and cholesterol free diet for 4 weeks to study mechanisms of plaque regression.

Results

Proliferation of scavenger receptor A and CD36 deficient macrophages with impaired lipid uptake was reduced by 30–50% in the plaque, while ABCA1/ABCG1 exporter deficiency resulted in cholesterol overloading and apoptosis. Oral atorvastatin treatment decreased total plasma cholesterol levels by 50% to the same extend as cholesterol free diet feeding in APOE*3-Leiden.huCETP. Cholesterol lowering resulted in a 50% reduction in local macrophage proliferation and plaque regression with reduced macrophage and lipid contents and increased collagen. GFP bone marrow reconstitution of APOE*3-Leiden.huCETP mice in which the aortas were shielded from irradiation showed infiltrating monocytes to contribute only 11% to the plaque macrophage pool during plaque progression, thereby underscoring the relevance of targeting macrophage proliferation for plaque regression. Finally, rates of macrophage proliferation in human carotid artery plaques correlated with serum LDL-cholesterol levels, in line with our experimental studies.

Conclusion

Foam cell formation in atherosclerotic plaques triggers their proliferation. Targeting macrophage proliferation leads to plaque regression.

5221Knockout of purinergic receptor Y13 (P2Y13) results in an improved outcome in metabolic syndrome in mice

Background

Metabolic syndrome clusters the main risk factors for cardiovascular diseases and endocrine dysfunction. Novel studies show that the important underlying mechanism is a long term inflammation of adipose tissue with a gradual shift from the anti-inflammatory M2 towards the pro-inflammatory M1 macrophages (pathognomonic). Massive hypertrophy induces adipocyte death, which releases DAMPs like nucleotides recognized by purinergic receptors orchestrating ongoing inflammatory process. Interestingly, we found Gi coupled P2Y13R only expressed on M1 macrophages, not in M0 (unstimulated) and M2 macrophages.

Nevertheless, the role of P2Y13R in the immune system and especially macrophages is currently unknown. Given its pivotal role in central metabolic processes (P2Y13R has been described in insulin secretory signalling) together with its unique expression in its pathognomonic inflammatory macrophage subtype makes it an interesting candidate to investigate its role in metabolic syndrome.

Purpose

Due to the unique expression of P2Y13R on M1 macrophages we hypothesise an improved outcome in a high-fat diet induced metabolic syndrome by interfering with the P2Y13 signalling cascade.

Methods

BMDM differentiation to macrophages using M-CSF and subsequent stimulation with medium (M0), LPS and IFNγ (M1) or IL4 (M2); Expression of P2Rs quantified using Taqman qPCR.

Male C57Bl6/J wild-type (WT) and P2Y13-deficient (KO) mice were fed with a high-fat diet (HFD) for 20 weeks; On week 15 we performed the ITT, on week 16 the GTT. Metabolic performance was monitored by metabolic caging.

Results

We observed a unique expression of P2Y13R on M1 macrophages. Adult P2Y13-deficient mice showed a higher O2 consumption compared to adult C57Bl6/J wild-type mice (AUC of O2 consumption 2nd day= KO: 61620±2261mL/kg vs WT: 53830±916.1mL/kg, p=0.0331). Although both P2Y13−/− mice and WT littermates consumed comparable amount of food (daily food intake per mouse → KO: 3.97±0.25g vs WT: 3.76±0.18g), P2Y13 deficient animals showed significantly decelerated weight gain (e.g. on week 15 → KO: 142±2% (n=10) vs WT: 198±5% (n=10), p<0.0001). Obese P2Y13−/− animals outperformed obese WT littermates in a peritoneal glucose tolerance test (2h after glucose injection → KO: 272.9±21.0 mg/dL (n=10) vs WT: 532.6±21.2 (n=10) mg/dL, p<0.0001). There was no difference in the cell amount of stromal vascular fraction cells.

Conclusion

Global P2Y13 deficiency leads to an improved outcome in metabolic syndrome with an increased protection against developing an insulin resistance as shown through an improved glucose tolerance and basal glucose levels, a decelerated weight gain despite comparable food consumption and a better metabolic turnover. Observing these beneficial metabolic improvements, we hypothesise that antagonization of P2Y13R could be a promising therapeutic target in the field of metabolic syndrome.

P6291Post-myocardial infarction activation of P2X7 dependent inflammasome is crucial to develop an appropriate scar integrity

Introduction

Cardiovascular diseases are the main cause of death worldwide. Acute ischemia results in cell death of cardiomyocytes accompanied with the release of so called damage associated molecular patterns (DAMPs) such as nucleotides. High concentration of ATP in the extracellular fluid leads to the opening of the ionotropic purinergic receptor P2X7. The following transmembranous ion flux triggers the assembly of the NLRP-3 inflammasome and proteolytic caspase-1 activation which cleaves pro-IL-1β and provokes the release of fully active pro-inflammatory IL-1β. Myocardial scar formation can be divided into an early remodelling IL-1β-dependent and a late scar forming TGFβ phase. Both phases negatively regulate each other. The current stuy aimed to investigate the role of this master regulator of NLRP3 inflammasome assembly P2Y7 in myocardial remodeling during prolonged ischemic conditions.

Methods

10 weeks old P2X7 knock-out and C57Bl6/J mice received a full ligation of the left anterior descending (LAD) artery. Mice three and seven days post-infarction underwent echocardiography. Myocardial scar formation was assessed by histological staining and flow cytometry. Furthermore caspase-1 activity was measured using FLICA in histology. Gene expression was assessed using TaqMan realtime PCR.

Results

Macrophages in the myocardial infarct area showed high P2X7 expression by Co-staining with fluorescent antibodies against F4/80, CD68 and P2X7. Intriguingyl P2X7 deficient animals showed a significantly worse survival rate in a Kaplan-Meier survival analysis compared to wt littermated with LAD ligation (Mortality after 21 days P2X7+/+ 50%; P2X7−/− 100%, p<0.05). Cause of death assessed by autopsy was myocardial rupture in P2X7−/− mice. Accordingly histological analysis revealed a less compact infarct area in P2X7 knock-out animals with abundant coagulation necrosis. In agreement with that we observed a thickened infarcted anterior wall by echocardiography in P2X7 animals. Furthermore whereas the infarcted area of P2X7 competent mice showed high signals for active caspase-1 in histology, we were not able to detect any signal of caspase-1 activity in P2X7 deficient mice. In coherence with this observation we detected a premature increased TGFβ gene transcript upregulation in infarct tissue of P2X7 deficient animals.

Conclusion

The knockout of the NLRP3 inflammasome activating P2X7 receptor impairs the outcome after myocardial infarction by reduced monocyte infiltration and deranged scar formation. Disruption of the fine-tuned IL-1β/TGFβ sequence with an early block of IL-1β signaling and premature TGFβ activation could explain the missing clean-up of necrotic debris and impaired scar formation. Taken together these findings highlight the importance of an early inflammasome phase during myocardial scar formation.

P6346Purinergic receptor Y6 (P2Y6) deficiency impairs left ventricular function

Introduction

Cardiomyopathies due to pathological remodelling are the most common myocardial disorders and leading indication for heart transplant in young adults. Cardiomyocytes rely on sessile macrophage phagocytosis for cell homeostasis. Purinergic receptor Y6, selectively binding to UDP, promotes phagocytosis and is involved in several tissue-remodelling processes.

We hypothesize a critical role of P2Y6 in the maintenance of cardiac tissue homeostasis in vivo.

Methods

Echocardiography was performed on male C57Bl6 wild-type (WT) and P2Y6-deficient (KO) mice at different ages up to 20 weeks. In addition, WT and KO mice underwent bone marrow transplantation. For histological analysis, hearts from WT and KO mice were stained with HE, Masson's trichrome, wheat germ agglutinin, CD11b, LC3B and TUNEL. Cardiac ultrastructure of WT and KO hearts was investigated by electron microscopic imaging. Furthermore, uptake of fluorescent pHrodo bioparticles by WT and KO bone marrow derived macrophages (BMDMs), either in presence or absence of specific P2Y6 agonist UDP or full antagonist MRS2578, was measured in vitro.

Results

KO mice were significantly impaired in their LV function by reduced ejection fraction (WT: 57.37±1.27%, n=13, KO: 44.13±1.09%, n=16, p<0.0001), stroke volume (WT+: 39.25±1.94μl, n=13, KO: 33.57±1.94μL, n=16, p<0.05), and cardiac output (WT: 20.79±1.11 mL/min, n=13, KO: 17.84±0.85 mL/min, n=16, p<0.05). A long-term follow-up revealed progressive impairment of the cardiac function (4 w: WT: 62.07±1.11%, n=5, KO: 48.73±1.03%, n=10, p<0.0001; 6 w: WT: 54.29±1.88%, n=5, KO: 44.61±1.4%, n=10, p<0.01; 8 w: WT: 56.43±1.44%, n=5, KO: 44.72±0.89%, n=10, p<0.0001). Echocardiography 6 weeks after bone marrow transplantation demonstrated convalescence upon reconstitution with WT bone marrow (WT in KO: 46.19±2.68%, n=3 vs KO in WT: 38.40±1.26%, n=3). No major differences with regard to morphology, cell size, collagen deposition, leukocyte infiltration or apoptosis were observed in histology. However, LC3B expression was increased in KO mice (mean fluorescent area: WT: 191.1±19.93μm2, n=5, KO: 261.2±18.34μm2, n=10, p<0.05). Electron microscopic imaging revealed a distinctly impaired ultrastructure with T-tubule remodelling, mitochondrial derangement and abnormal numbers of autophagosomes in KO hearts. In vitro, fluorescent particle phagocytosis by BMDMs was completely blocked after treatment with MRS2578.

Conclusion

Global P2Y6 deficiency leads to a progressive cardiomyopathy in mice, mainly characterized by an impaired left ventricular function and ultrastructural irregularities. Its exacerbation seems to be prevented by reconstitution with WT bone marrow. For the underlying mechanism, we conclude a deranged cardiomyocyte homeostasis in KO animals due to defective phagocytic activity of resident macrophages. Potential induction of cardiac clearance via P2Y6 signalling could be a promising therapeutic target in the field of cardiomyopathies.

P1939Tumor necrosis factor receptor-associated factor 5 (TRAF-5) deficiency exacerbates diet-induced adipose tissue inflammation and aggravates metabolic syndrome in mice

Introduction

Many clinical and experimental observations have established an association between visceral obesity and chronic adipose tissue inflammation. Potent pro-inflammatory mediators such as TNFα, CD40 and IL-1β are regulated by Tumor necrosis factor (TNF) receptor-associated factors (TRAFs). TRAF5 deficiency accelerates atherogenesis in mice by increasing inflammatory leukocyte recruitment. Since inflammatory cell invasion is also a prerequisite of adipose tissue inflammation, we tested the hypothesis that deficient TRAF5 signaling aggravates adipose tissue inflammation and its metabolic complications in a murine diet-induced obesity (DIO) model.

Purpose

We aimed to clarify the role of TRAF5 in adipose tissue inflammation and metabolic syndrome.

Methods

TRAF5−/− mice and gender- and age-matched wild-type (WT) mice consumed a high fat diet (HFD, 45%kcal from fat) or a matched low-fat diet (LFD, 10%kcal from fat) for 18 weeks to induce DIO and adipose tissue inflammation. All mice were then subjected to subsequent analysis, including glucose and insulin tolerance testing, body composition assessment by MRI imaging, flow cytometry, gene expression of different tissues, plasma analysis and histology. Finally, we studied if TRAF5 expression was associated with metabolic syndrome in humans by analyzing plasma and adipocytes samples from 62 patients of the Tumor-Necrosis-Factor Receptor Associated in Cardiovascular Risk Study (TRAFICS).

Results

TRAF5 expression was significantly attenuated in isolated WT-adipocytes and WT-macrophages after 18 weeks of HFD compared to LFD-fed controls. TRAF5−/− mice on HFD gained significantly more weight compared to TRAF5-competent mice and showed an aggravated metabolic phenotype, including impaired insulin tolerance, hyperinsulinemia and increased fasting glucose plasma levels. The weight gain in TRAF5−/− mice was attributable to a significant increase in adipose tissue and liver weight. Further analysis of the visceral adipose tissue revealed enhanced macrophage accumulation and increased pro-inflammatory CD11c+ subset polarization in HFD-fed TRAF5−/− mice. In line with an increased migratory capacity of inflammatory cells, we observed enhanced peritoneal invasion of leukocytes and subsets in TRAF5−/− mice. Accordingly, TRAF5 deficiency increased inflammatory cytokine expression and ameliorated parameters of insulin sensitivity in adipose tissue. Finally, patients with metabolic syndrome displayed decreased TRAF5 expression in blood and adipocytes compared to humans without metabolic syndrome.

Conclusion

We show that genetic deficiency of TRAF5 aggravates metabolic syndrome in murine diet-induced obesity. Enhanced accumulation of leukocytes subsets in adipose tissue serves as the likely mechanism. We conclude that TRAF5 signaling properties may favorably affect metabolic disease.

Acknowledgement/Funding

Forschungskommission Medizinische Fakultät Universität Freiburg, MOTI-VATE Promotionskolleg der Medizinischen Fakultät Freiburg (EKFS)

[Current medicolegal and ethical issues in pathology]

The increase in density of information available in relation to patients and research participants, in particular in the context of genetic diagnostics and analysis, results in an increased potential for uncovering details which were unexpected but are of particular significance for the patient. Deciding how this information is dealt with and who is entitled to receive this information, is a medicolegal and ethical balancing act. Incidental findings and the challenges posed by the advent of personalised medicine are but two areas which increasingly impact medical disciplines that do not conventionally work directly with patients. Both areas raise questions of what is legally required and morally necessary. The authors briefly sketch these two areas and the medicolegal and ethical implications for diagnostics and research in pathology.