Motion of VAPB molecules reveals ER-mitochondria contact site subdomains

To coordinate cellular physiology, eukaryotic cells rely on the rapid exchange of molecules at specialized organelle-organelle contact sites1,2. Endoplasmic reticulum-mitochondrial contact sites (ERMCSs) are particularly vital communication hubs, playing key roles in the exchange of signalling molecules, lipids and metabolites3,4. ERMCSs are maintained by interactions between complementary tethering molecules on the surface of each organelle5,6. However, due to the extreme sensitivity of these membrane interfaces to experimental perturbation7,8, a clear understanding of their nanoscale organization and regulation is still lacking. Here we combine three-dimensional electron microscopy with high-speed molecular tracking of a model organelle tether, Vesicle-associated membrane protein (VAMP)-associated protein B (VAPB), to map the structure and diffusion landscape of ERMCSs. We uncovered dynamic subdomains within VAPB contact sites that correlate with ER membrane curvature and undergo rapid remodelling. We show that VAPB molecules enter and leave ERMCSs within seconds, despite the contact site itself remaining stable over much longer time scales. This metastability allows ERMCSs to remodel with changes in the physiological environment to accommodate metabolic needs of the cell. An amyotrophic lateral sclerosis-associated mutation in VAPB perturbs these subdomains, likely impairing their remodelling capacity and resulting in impaired interorganelle communication. These results establish high-speed single-molecule imaging as a new tool for mapping the structure of contact site interfaces and reveal that the diffusion landscape of VAPB at contact sites is a crucial component of ERMCS homeostasis.

Aberrant axon initial segment plasticity and intrinsic excitability of ALS hiPSC motor neurons

Dysregulated neuronal excitability is a hallmark of amyotrophic lateral sclerosis (ALS). We sought to investigate how functional changes to the axon initial segment (AIS), the site of action potential generation, could impact neuronal excitability in ALS human induced pluripotent stem cell (hiPSC) motor neurons. We find that early TDP-43 and C9orf72 hiPSC motor neurons show an increase in the length of the AIS and impaired activity-dependent AIS plasticity that is linked to abnormal homeostatic regulation of neuronal activity and intrinsic hyperexcitability. In turn, these hyperactive neurons drive increased spontaneous myofiber contractions of in vitro hiPSC motor units. In contrast, late hiPSC and postmortem ALS motor neurons show AIS shortening, and hiPSC motor neurons progress to hypoexcitability. At a molecular level, aberrant expression of the AIS master scaffolding protein ankyrin-G and AIS-specific voltage-gated sodium channels mirror these dynamic changes in AIS function and excitability. Our results point toward the AIS as an important site of dysfunction in ALS motor neurons.

A scalable human iPSC-based neuromuscular disease model on suspended biobased elastomer nanofiber scaffolds

Many devastating neuromuscular diseases currently lack effective treatments. This is in part due to a lack of drug discovery platforms capable of assessing complex human neuromuscular disease phenotypes in a scalable manner. A major obstacle has been generating scaffolds to stabilise mature contractile myofibers in a multi-well assay format amenable to high content image (HCI) analysis. This study describes the development of a scalable human induced pluripotent stem cell (iPSC)-neuromuscular disease model, whereby suspended elastomer nanofibers support long-term stability, alignment, maturation, and repeated contractions of iPSC-myofibers, innervated by iPSC-motor neurons in 96-well assay plates. In this platform, optogenetic stimulation of the motor neurons elicits robust myofiber-contractions, providing a functional readout of neuromuscular transmission. Additionally, HCI analysis provides rapid and automated quantification of axonal outgrowth, myofiber morphology, and neuromuscular synapse number and morphology. By incorporating amyotrophic lateral sclerosis (ALS)-related TDP-43G298Smutant motor neurons and CRISPR-corrected controls, key neuromuscular disease phenotypes are recapitulated, including weaker myofiber contractions, reduced axonal outgrowth, and reduced number of neuromuscular synapses. Treatment with a candidate ALS drug, the receptor-interacting protein kinase-1 (RIPK1)-inhibitor necrostatin-1, rescues these phenotypes in a dose-dependent manner, highlighting the potential of this platform to screen novel treatments for neuromuscular diseases.

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

Laparoscopic Heller-Dor is an effective long-term treatment for end-stage achalasia

BACKGROUND

The end-stage achalasia is a difficult condition to treat, for the esophageal diameter and conformation of the gullet, that may progress to a sigmoid shape. The aim of this study was to examine the outcome of Laparoscopic Heller-Dor in patients with end-stage achalasia, comparing them with patients who had mega-esophagus without a sigmoid shape.

METHODS

From 1992 to 2020, patients with a diagnosis of sigmoid esophagus, or radiological stage IV achalasia (the SE group), and patients with a straight esophagus larger than 6 cm in diameter, or radiological stage III achalasia (the NSE group), were all treated with LHD. The two groups were compared in terms of patients' symptoms, based on the Eckardt score, and on barium swallow, endoscopy and manometry performed before and after the treatment. The failure of the treatment was defined as an Eckardt score > 3, or the need for further treatment.

RESULTS

The study involved 164 patients: 73 in the SE group and 91 in the NSE group. No intra- or postoperative mortality was recorded. The median follow-up was 51 months (IQR 25-107). The outcome was satisfactory in 71.2% of patients in the SE group, and in 89% of those in the NSE group (p = 0.005).

CONCLUSIONS

SE is certainly the worst condition of the disease and the final outcome of LHD, in term of symptom control, is inferior compared to NSE. Despite this, almost 3/4 of the SE patients experienced a significant relieve in symptoms after LHD, which may therefore still be the first surgical option to offer to these patients, before considering esophagectomy.

Enrichment of human embryonic stem cell-derived V3 interneurons using an Nkx2-2 gene-specific reporter

V3 spinal interneurons are a key element of the spinal circuits, which control motor function. However, to date, there are no effective ways of deriving a pure V3 population from human pluripotent stem cells. Here, we report a method for differentiation and isolation of spinal V3 interneurons, combining extrinsic factor-mediated differentiation and magnetic activated cell sorting. We found that differentiation of V3 progenitors can be enhanced with a higher concentration of Sonic Hedgehog agonist, as well as culturing cells in 3D format. To enable V3 progenitor purification from mixed differentiation cultures, we developed a transgene reporter, with a part of the regulatory region of V3-specific gene Nkx2-2 driving the expression of a membrane marker CD14. We found that in human cells, NKX2-2 initially exhibited co-labelling with motor neuron progenitor marker, but V3 specificity emerged as the differentiation culture progressed. At these later differentiation timepoints, we were able to enrich V3 progenitors labelled with CD14 to ~ 95% purity, and mature them to postmitotic V3 interneurons. This purification tool for V3 interneurons will be useful for in vitro disease modeling, studies of normal human neural development and potential cell therapies for disorders of the spinal cord.

RGD density along with substrate stiffness regulate hPSC hepatocyte functionality through YAP signalling

Human pluripotent stem cell-derived hepatocytes (hPSC-Heps) may be suitable for treating liver diseases, but differentiation protocols often fail to yield adult-like cells. We hypothesised that replicating healthy liver niche biochemical and biophysical cues would produce hepatocytes with desired metabolic functionality. Using 2D synthetic hydrogels which independently control mechanical properties and biochemical cues, we found that culturing hPSC-Heps on surfaces matching the stiffness of fibrotic liver tissue upregulated expression of genes for RGD-binding integrins, and increased expression of YAP/TAZ and their transcriptional targets. Alternatively, culture on soft, healthy liver-like substrates drove increases in cytochrome p450 activity and ureagenesis. Knockdown of ITGB1 or reducing RGD-motif-containing peptide concentration in stiff hydrogels reduced YAP activity and improved metabolic functionality; however, on soft substrates, reducing RGD concentration had the opposite effect. Furthermore, targeting YAP activity with verteporfin or forskolin increased cytochrome p450 activity, with forskolin dramatically enhancing urea synthesis. hPSC-Heps could also be successfully encapsulated within RGD peptide-containing hydrogels without negatively impacting hepatic functionality, and compared to 2D cultures, 3D cultured hPSC-Heps secreted significantly less fetal liver-associated alpha-fetoprotein, suggesting furthered differentiation. Our platform overcomes technical hurdles in replicating the liver niche, and allowed us to identify a role for YAP/TAZ-mediated mechanosensing in hPSC-Hep differentiation.

Results of a prospective observational study of autologous peripheral blood mononuclear cell therapy for no-option critical limb-threatening ischemia and severe diabetic foot ulcers

Background

Cell therapy with autologous peripheral blood mononuclear cells (PB-MNCs) may help restore limb perfusion in patients with diabetes mellitus and critical limb-threatening ischemia (CLTI) deemed not eligible for revascularization procedures and consequently at risk for major amputation (no-option). Fundamental is to establish its clinical value and to identify candidates with a greater benefit over time. Assessing the frequency of PB circulating angiogenic cells and extracellular vesicles (EVs) may help in guiding candidate selection.

Methods

We conducted a prospective, non-controlled, observational study on no-option CLTI diabetic patients that underwent intramuscular PB-MNCs therapy, which consisted of more cell treatments repeated a maximum of three times. The primary endpoint was amputation rate at 1 year following the first treatment with PB-MNCs. We evaluated ulcer healing, walking capability, and mortality during the follow-up period. We assessed angiogenic cells and EVs at baseline and after each cell treatment, according to primary outcome and tissue perfusion at the last treatment [measured as transcutaneous oxygen pressure (TcPO₂)].

Results

50 patients were consecutively enrolled and the primary endpoint was 16%. TcPO₂ increased after PB-MNCs therapy (17.2 ± 11.6 vs 39.1 ± 21.8 mmHg, p < .0001), and ulcers healed with back-to-walk were observed in 60% of the study population (88% of survivors) during follow-up (median 1.5 years). Patients with a high level of TcPO₂ (≥ 40 mmHg) after the last treatment showed a high frequency of small EVs at enrollment.

Conclusions

In no-option CLTI diabetic patients, PB-MNCs therapy led to an improvement in tissue perfusion, a high rate of healing, and back-to-walk. Coupling circulating cellular markers of angiogenesis could help in the identification of patients with a better clinical benefit over time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01629-y.

Esophageal Achalasia: Diagnostic Evaluation

A precise diagnosis is key to the successful treatment of achalasia. Barium swallow, upper endoscopy and high-resolution manometry provide the necessary information about a patient's anatomy, absence of other diseases, and type of achalasia (I, II, III). High-resolution manometry also has prognostic value, the best results of treatment being obtained in type II achalasia according to the Chicago classification. Abdominal CT scanning and endoscopic ultrasound might be warranted if an underlying malignancy is suspected.

AB1198 PREVALENCE AND PSYCHOPATHOLOGICAL CHARACTERISTICS OF ANXIETY AND DEPRESSIVE SYMPTOMS IN FIBROMYALGIA PATIENTS

Background

Several studies reported higher depression and anxiety rates in fibromyalgia (FM) patients compared to the general population. Furthermore, dysfunctional coping strategies

have been pointed to as intrinsic parts of the pathogenesis of FM.

Objectives

Our study aimed to verify the prevalence of anxiety and depressive symptoms and explore their correlation with physical symptoms as fatigue, sleep, and widespread pain in a cohort of patients diagnosed with FM. We also aimed to determine whether dysfunctional coping strategies might increase the depression and anxiety burden, besides worsening the core symptoms of FM.

Methods

We analyzed a cohort of 105 patients (median age of 53 years 6 M, 99 F) with a diagnosis of FM according to the ACR 2016 criteria. The participants were consecutively recruited from the Fibromyalgia clinic of the University of Campania “Luigi Vanvitelli”. All patients underwent a psychiatric evaluation. We assessed widespread pain by the Widespread Pain Index (WPI) and the presence of fatigue by the Symptom Severity score (SS). Sleep disorders were investigated through Pittsburgh Sleep Quality Index (PSQI). We analyzed mental alterations by Hamilton Depression and Anxiety Rating Scales (HAM-D, HAM-A), and coping strategies by Coping Orientation to Problems Experienced (COPE) Inventory.

The Statistical Package for Social Sciences (SPSS) 22.0 was used; the level of significance was set at p < 0.05.

Results

All patients showed fatigue and widespread pain (100%); sleep disturbances were found in 90.5% of patients and overlapped with all sleep phases. The prevalence of anxiety associated with depression was 75.2%. We found isolated anxiety in 14.3% and isolated depression in 4.8% of patients. We further evidenced a different degree of depression: mild (50.7%), moderate (24.3%), and severe (6.5%). All patients showed depressed mood only if questioned (low tendency to spontaneous verbalization). COPE analysis showed no significant differences in the use of the three coping strategies (Problem-focused, emotion-focused, avoidance-focused). Pearson’s correlation analysis highlighted a negative relationship between problem-focused strategies and the severity of anxiety (r = -0.31, p = .001) and depression (r = -0.32, p = .001). Our analysis also highlighted a positive correlation between fatigue, sleep disturbances, widespread pain, and both anxiety and depression. The analysis of the characteristics of anxiety and depressive symptoms showed a scarce tendency to spontaneous verbalization of depressed mood and ideas of guilt, mostly limited to family relationships, and a sense of ineffectiveness conditioned by the physical symptoms of the disease. Most patients showed psychomotor agitation, psychic and somatic anxiety, poor insight. The analysis of coping strategies adopted showed a negative correlation between problem-focused strategies and anxiety-depressive symptoms, suggesting that such strategies are less frequent in FM patients with comorbid anxiety and depressive symptoms.

Conclusion

Our study confirms the high prevalence of anxiety and depressive symptoms in FM patients. A positive correlation between the pivotal symptoms and anxiety and depressive symptoms may suggest, without implying a cause-and-effect relationship, that psychiatric intervention should be considered along with rheumatologic treatment, to improve both physical symptoms and quality of life. Potentiating problem-focused coping strategies may represent a target to improve anxiety and depressive symptoms.

References

[1]Wolfe et al Revisions to the 2010/2011 FM diagnostic criteria. Semin Arth. Rheum. 2016

Table 1.

Correlation analysis between coping strategies and HAM-D and HAM-A total scores

HAM-DHAM- AProblem-focused Coping- 0,32**- 0,31**Avoidant Coping0,800,92Emotion Coping0,140,13

**p<0.01

Disclosure of Interests

None declared

POS1211 SEROLOGICAL RESPONSE TO BNT162b2 mRNA ANTI-SARS-CoV-2 VACCINATION IN PATIENTS WITH INFLAMMATORY RHEUMATIC DISEASES: RESULTS FROM THE RHEUVAX COHORT

Background

To date, globally considered, the literature suggests that AIRD may be at higher risk of infection and death due to COVID19 compared to the general population. Vaccination against SARS-CoV-2 reduces the risk of hospitalization and mortality. However, immunological alteration associated with Autoimmune Inflammatory Rheumatic Diseases (AIRD) and immunosuppressive medications may impair the response to vaccination. Emerging data suggest that immunosuppressive treatment may negatively impact the response to anti-SARS-CoV-2 vaccines in the AIRD population; data are robust for some treatments, more controversial for others.

Identifying patients at higher risk of lack of protection is essential for shielding them and for adapting therapeutic protocol and vaccination timing.

Objectives

In the light of the current COVID19 epidemic and the availability of effective vaccines, this study aims to identify predictors of non-response to anti-SARS-CoV-2 vaccines in patients affected by AIRD.

Methods

An observational cross-sectional study was conducted evaluating the serological response and the persistence of antibodies at eight weeks in IRD patient cohort and non-IRD control.

IRD and age and sex-matched controls volunteer among the health professionals (CTRL) who underwent vaccination with two doses of BNT162b2 were recruited for this study. Anti-Trimeric Spike protein antibodies were assayed eight ± one week after the second vaccine dose. Univariate and logistic regression analyses were performed to identify predictors of non-response and low antibody titers.

Results

Samples were obtained from 237 IRD patients (m/f 73/164, mean age 57, CI 95% [56-59]): 4 autoinflammatory diseases (AI), 62 connective tissue diseases (CTD), 86 rheumatoid arthritis (RA), 71 spondylarthritis (SpA) and 14 vasculitis (Vsc). 232 CTRL were recruited (m/f 71/161, mean age 57, CI 95% [56-58]).

Globally, IRD had a lower seroconversion rate (88.6% vs 99.6%, CI 95% OR [1.61-5.73], p<0.0001) and lower antibody titer compared to controls (median (IQR) 403 (131.5-1012) vs 1160 (702.5-1675), p<0.0001). After logistic regression, age, corticosteroid (CCS), Abatacept (ABA), and Mycophenolate Mofetil (MMF) use were predictors of non-response.

The antibody titers eight weeks after the second dose of vaccine were lower in AIRD compared to controls, median (IQR) 403 (131.5-1012) vs 1160 (702.5-1675), p<0.0001 with no difference between sexes and age groups. CTD, RA and SpA had lower antibodies levels. However, the logistic regression model identified treatment with MMF, ABA, CCS, Methotrexate (MTX), Rituximab (RTX), Janus Kinase inhibitors (JAKi) and TNF inhibitors (TNFi) as independent predictors of serum titer. ABA, RTX, MMF, and MTX had the strongest effect size.

Conclusion

The response to anti-SARS-CoV-2 vaccines is often impaired in AIRD patients under treatment and may pose them at higher risk of severe COVID-19. Although this work focused on serological response, most of the treatment the impaired vaccine response are known to act on T cells, possibly also influencing the cellular response. Evidence-based protocols are required to time vaccination and treatment to improve immunization of AIRD patients.

References

[1]Kroon, F. P. B. et al. Risk and prognosis of SARS-CoV-2 infection and vaccination against SARS-CoV-2 in rheumatic and musculoskeletal diseases: a systematic literature review to inform EULAR recommendations. Ann. Rheum. Dis. (2021).

Acknowledgements

The authors would like to thank Dr Daniela Iacono, Dr Carlo Iandoli, Dr Alessandra Milone, Dr Anna Pellegrlino, Dr Elisabetta Seguino and Mrs Maria Puca, for their contribution in data and blood samples collection, Dr Giorgia Della Polla for the valuable suggestions on data analysis. The authors are grateful also to all patients and the volunteers for their contribution.

Disclosure of Interests

None declared

AB0463 PREVALENCE AND PREDICTORS OF COGNITIVE DYSFUNCTION IN PATIENTS WITH LUPUS NEPHRITIS: A CROSS-SECTIONAL COMPARISON WITH PATIENTS WITH OTHER CHRONIC KIDNEY DISEASES

Background

Cognitive dysfunction (CD) is among the most frequent neuropsychiatric manifestation of systemic lupus erythematosus (SLE) that has a considerable impact on quality of life, but still lacks adequate screening in clinical routine.

Objectives

Our aim was to investigate the distribution and determinants of CD in patients with lupus nephritis, and to compare cognitive function with that in patients with other forms of glomerular chronic kidney disease (CKD) by the Montréal Cognitive Assessment (MoCA).

Methods

We carried out a cross-sectional case-control study with consecutive patients with SLE who fulfilled the 2012 SLICC (Systemic Lupus International Collaborating Clinics) classification criteria(1) and have history of lupus nephritis, using a similarly derived CKD control population matched by age and sex, to assess cognitive function using MoCA scale(2). CD was defined as score < 26/30, adjusted for duration of formal education. Demographic data and disease characteristics were collected. SLE disease activity was evaluated by using Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI2K) (3). The effect of disease-related parameters on the MoCA was examined by regression analysis.

Results

A total of 35 patients with SLE and 35 CKD controls were included in our study (Table 1). Among SLE patients, 7 (20%) patients had biopsy proven active nephritis, 7 (20%) had kidney failure and one a kidney transplant. CD according to MoCA score was found in 64.2% (n=45) patients (Figure 1). The proportion of patients with CD according to MoCA between patients with lupus nephritis and CKD controls was not statistically significant (62.8% vs 65.7%, p>0.05). SLE patients performed bad in all cognitive domains. Memory, abstraction and language skills were the most affected domains. Our study showed that active nephritis and disease duration were associated with poor cognitive performance (OR=1.4, p = 0.03; OR=1.2, p = 0.03). GFR values and other parameters evaluated (end stage renal disease, damage, age at diagnosis, use of glucocorticoids, hydroxychloroquine and immunosuppressive drugs) had no significant effect on development of CD in SLE patients.

Table 1.

Demographics and clinical characteristics of SLE patients

mean%Age44Women94.2Education>16 yrs51.416 -13 yrs37.1<13 yrs11.4Disease duration (yrs)16Kidney failure20Prednisone (% use)<20 mg11.4≥20mg88.5Hydroxychloroquine (% use)65.7Immunosuppressants (% use)57.1SLEDAI2.4SDI0.8Figure 1.

Montréal Cognitive Assessment (MoCA) results in patients with systemic lupus erythematosus (SLE) compared to hemodialysis and chronic kidney disease (CKD) patients.

Conclusion

In this study, two thirds of SLE patients had CD. Patients with lupus nephritis have comparable cognitive function than patients with other CKD. Decline in renal function was not associated with CD in SLE, suggesting that the CD in this population may represent a consequence of lupus itself rather than kidney-related central nervous system damage.

References

[1]Petri M, et al. Arthritis Rheum. 2012

[2]Nasreddine ZS, et al. J Am Geriatr Soc 2005

[3]Gladman DD, et al. J Rheumatol. 2002

Disclosure of Interests

None declared

Biobased Elastomer Nanofibers Guide Light-Controlled Human-iPSC-Derived Skeletal Myofibers

Generating skeletal muscle tissue that mimics the cellular alignment, maturation, and function of native skeletal muscle is an ongoing challenge in disease modeling and regenerative therapies. Skeletal muscle cultures require extracellular guidance and mechanical support to stabilize contractile myofibers. Existing microfabrication-based solutions are limited by complex fabrication steps, low throughput, and challenges in measuring dynamic contractile function. Here, the synthesis and characterization of a new biobased nanohybrid elastomer, which is electrospun into aligned nanofiber sheets to mimic the skeletal muscle extracellular matrix, is presented. The polymer exhibits remarkable hyperelasticity well-matched to that of native skeletal muscle (≈11-50 kPa), with ultimate strain ≈1000%, and elastic modulus ≈25 kPa. Uniaxially aligned nanofibers guide myoblast alignment, enhance sarcomere formation, and promote a ≈32% increase in myotube fusion and ≈50% increase in myofiber maturation. The elastomer nanofibers stabilize optogenetically controlled human induced pluripotent stem cell derived skeletal myofibers. When activated by blue light, the myofiber-nanofiber hybrid constructs maintain a significantly higher (>200%) contraction velocity and specific force (>280%) compared to conventional culture methods. The engineered myofibers exhibit a power density of ≈35 W m-3 . This system is a promising new skeletal muscle tissue model for applications in muscular disease modeling, drug discovery, and muscle regeneration.

Ejection of damaged mitochondria and their removal by macrophages ensure efficient thermogenesis in brown adipose tissue

Recent findings have demonstrated that mitochondria can be transferred between cells to control metabolic homeostasis. Although the mitochondria of brown adipocytes comprise a large component of the cell volume and undergo reorganization to sustain thermogenesis, it remains unclear whether an intercellular mitochondrial transfer occurs in brown adipose tissue (BAT) and regulates adaptive thermogenesis. Herein, we demonstrated that thermogenically stressed brown adipocytes release extracellular vesicles (EVs) that contain oxidatively damaged mitochondrial parts to avoid failure of the thermogenic program. When re-uptaken by parental brown adipocytes, mitochondria-derived EVs reduced peroxisome proliferator-activated receptor-γ signaling and the levels of mitochondrial proteins, including UCP1. Their removal via the phagocytic activity of BAT-resident macrophages is instrumental in preserving BAT physiology. Depletion of macrophages in vivo causes the abnormal accumulation of extracellular mitochondrial vesicles in BAT, impairing the thermogenic response to cold exposure. These findings reveal a homeostatic role of tissue-resident macrophages in the mitochondrial quality control of BAT.

When a Friend Becomes Your Enemy: Natural Killer Cells in Atherosclerosis and Atherosclerosis-Associated Risk Factors

Atherosclerosis (ATS), the change in structure and function of arteries with associated lesion formation and altered blood flow, is the leading cause of cardiovascular disease, the number one killer worldwide. Beyond dyslipidemia, chronic inflammation, together with aberrant phenotype and function of cells of both the innate and adaptive immune system, are now recognized as relevant contributors to atherosclerosis onset and progression. While the role of macrophages and T cells in atherosclerosis has been addressed in several studies, Natural Killer cells (NKs) represent a poorly explored immune cell type, that deserves attention, due to NKs’ emerging contribution to vascular homeostasis. Furthermore, the possibility to re-polarize the immune system has emerged as a relevant tool to design new therapies, with some succesfull exmples in the field of cancer immunotherapy. Thus, a deeper knowledge of NK cell pathophysiology in the context of atherosclerosis and atherosclerosis-associated risk factors could help developing new preventive and treatment strategies, and decipher the complex scenario/history from “the risk factors for atherosclerosis” Here, we review the current knowledge about NK cell phenotype and activities in atherosclerosis and selected atherosclerosis risk factors, namely type-2 diabetes and obesity, and discuss the related NK-cell oriented environmental signals.

A Resource for the Network Representation of Cell Perturbations Caused by SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic has caused more than 2.3 million casualties worldwide and the lack of effective treatments is a major health concern. The development of targeted drugs is held back due to a limited understanding of the molecular mechanisms underlying the perturbation of cell physiology observed after viral infection. Recently, several approaches, aimed at identifying cellular proteins that may contribute to COVID-19 pathology, have been reported. Albeit valuable, this information offers limited mechanistic insight as these efforts have produced long lists of cellular proteins, the majority of which are not annotated to any cellular pathway. We have embarked in a project aimed at bridging this mechanistic gap by developing a new bioinformatic approach to estimate the functional distance between a subset of proteins and a list of pathways. A comprehensive literature search allowed us to annotate, in the SIGNOR 2.0 resource, causal information underlying the main molecular mechanisms through which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and related coronaviruses affect the host-cell physiology. Next, we developed a new strategy that enabled us to link SARS-CoV-2 interacting proteins to cellular phenotypes via paths of causal relationships. Remarkably, the extensive information about inhibitors of signaling proteins annotated in SIGNOR 2.0 makes it possible to formulate new potential therapeutic strategies. The proposed approach, which is generally applicable, generated a literature-based causal network that can be used as a framework to formulate informed mechanistic hypotheses on COVID-19 etiology and pathology.

Misalignment of hemodynamic forces in the left ventricle is associated with adverse remodeling following STEMI

Funding Acknowledgements

Type of funding sources: None.

Background

Infarct size (IS), area at risk (AAR) and microvascular obstruction (MVO) are well known predictors of adverse remodeling (aLVr) following acute myocardial infarction, while the pathogenic role of left ventricular (LV) hemodynamic forces (HDFs) is still unknown. Recent evidence suggests the role of HDFs in negative remodeling after pathogenic events. 

Purpose

To identify LV HDFs patterns associated with aLVr in reperfused ST-segment elevation MI (STEMI) patients.

Methods

Forty-nine acute STEMI patients underwent CMR at 1 week (baseline) and 4 months (follow-up) after MI.  The following parameters were measured: left ventricular end-diastolic and end-systolic volume index for body surface area (LVEDVi and LVESVi), left ventricular ejection fraction (LVEF) and LV mass index, AAR and IS. LV HDFs were computed at baseline from cine CMR long axis datasets using a novel method based on LV endocardial boundary tracking. LV HDFs were calculated both in apex-base (A-B) and latero-septal (L-S) directions. The distribution of LV HDFs were evaluated by L-S over A-B HDFs ratio (L-S/A-B HDFs ratio %). All HDFs parameters are computed over the entire heartbeat, in systole and diastole. aLVr was defined as an absolute increase in LVESV of at least 15% (ΔLV-ESV ≥15%).

Results

Patients with aLVr (n = 18; 37%) had significant greater value of AAR (32 ± 23 vs 22 ± 18; p = 0.03) and slightly larger IS (23 ± 16 vs 15 ± 11; p= 0.07) at baseline. In patients with aLVr at FU, baseline systolic L-S HDF were lower (2.7 ± 0.9 vs 3.6 ± 1; p = 0.027) while diastolic L-S/A-B HDF ratio was significantly higher (28 ± 14 vs 19 ± 6; p = 0.03), reflecting higher grade of diastolic HDFs misalignment. At univariate logistic regression analysis, higher IS [Odd ratio (OR) 1.05; 95% confidence interval (95% CI) 1.01-1.1; p= 0.04] L-S HDFs (OR 0.41; 95% CI 0.2-0.9; p= 0.04] and higher diastolic L-S/A-B HDFs ratio (OR 1.1; 95% CI 1.01-1.2; p= 0.05) were associated with aLVr at FU (Table).  At multivariate logistic regression analysis, L-S/A-B HDF ratio remained the only independent predictor of adverse LV remodeling after correction for other baseline determinants.

Conclusion

Misalignment of diastolic HDFs following STEMI is associated with aLVr observed after 4 months.

Predictors of adverse remodeling Univariate Multivariate Parameter OR (95% CI) P OR (95% CI) P IS (%) 1.05 (1.01-1.1) 0.042 - - Systolic L-S HDF 0.41 (0.2-0.9) 0.04 - - Diastolic L-S/A-B HDF Ratio 1.1 (1.01-1.2) 0.05 1.1 (1.01-1.2) 0.04 A-B:apex-base; L-S: latero-septal; HDFs: hemodynamic forces Abstract Figure. Diastolic HDFs distribution and aLVr

SCA-1 micro-heterogeneity in the fate decision of dystrophic fibro/adipogenic progenitors

The term micro-heterogeneity refers to non-genetic cell to cell variability observed in a bell-shaped distribution of the expression of a trait within a population. The contribution of micro-heterogeneity to physiology and pathology remains largely uncharacterised. To address such an issue, we investigated the impact of heterogeneity in skeletal muscle fibro/adipogenic progenitors (FAPs) isolated from an animal model of Duchenne muscular dystrophy (DMD), the mdx mouse. FAPs play an essential role in muscle homoeostasis. However, in pathological conditions or ageing, they are the source of intramuscular infiltrations of fibrotic or adipose tissue. By applying a multiplex flow cytometry assay, we characterised and purified from mdx muscles two FAP cell states expressing different levels of SCA-1. The two cell states are morphologically identical and repopulate each other after several growth cycles. However, they differ in their in vitro behaviour. Cells expressing higher levels of SCA-1 (SCA1-High-FAPs) differentiate more readily into adipocytes while, when exposed to a fibrogenic stimulation, increase the expression of Col1a1 and Timp1 mRNA. A transcriptomic analysis confirmed the adipogenic propensity of SCA1-High-FAPs. In addition, SCA1-High-FAPs proliferate more extensively ex vivo and display more proliferating cells in dystrophic muscles in comparison to SCA1-Low-FAPs. Adipogenesis of both FAP cell states is inhibited in vitro by leucocytes from young dystrophic mice, while leucocytes isolated from aged dystrophic mice are less effective in limiting the adipogenesis of SCA1-High-FAPs suggesting a differential regulatory effect of the microenvironment on micro-heterogeneity. Our data suggest that FAP micro-heterogeneity is modulated in pathological conditions and that this heterogeneity in turn may impact on the behaviour of interstitial mesenchymal cells in genetic diseases.

Skeletal Muscle-Derived Human Mesenchymal Stem Cells: Influence of Different Culture Conditions on Proliferative and Myogenic Capabilities

Skeletal muscle tissue is characterized by restrained self-regenerative capabilities, being ineffective in relation to trauma extension both in time span (e.g., chronic diseases) and in size (e.g., large trauma). For these reasons, tissue engineering and/or cellular therapies represent a valuable solution in the cases where the physiological healing process failed. Satellite cells, the putative skeletal muscle stem cells, have been the first solution explored to remedy the insufficient self-regeneration capacity. Nevertheless, some limitation related to donor age, muscle condition, expansion hitch, and myogenic potentiality maintenance have limited their use as therapeutic tool. To overcome this hindrance, different stem cells population with myogenic capabilities have been investigated to evaluate their real potentiality for therapeutic approaches, but, as of today, the perfect cell candidate has not been identified yet. In this work, we analyze the characteristics of skeletal muscle-derived human Mesenchymal Stem Cells (hMSCs), showing the maintenance/increment of myogenic activity upon differential culture conditions. In particular, we investigate the influence of a commercial enriched growth medium (Cyto-Grow), and of a medium enriched with either human-derived serum (H.S.) or human Platelet-rich Plasma (PrP), in order to set up a culture protocol useful for employing this cell population in clinical therapeutic strategies. The presented results reveal that both the enriched medium (Cyto-Grow) and the human-derived supplements (H.S. and PrP) have remarkable effects on hMSCs proliferation and myogenic differentiation compared to standard condition, uncovering the real possibility to exploit these human derivatives to ameliorate stem cells yield and efficacy.

Mechanisms, Hallmarks, and Implications of Stem Cell Quiescence

Cellular quiescence is a dormant but reversible cellular state in which cell-cycle entry and proliferation are prevented. Recent studies both in vivo and in vitro demonstrate that quiescence is actively maintained through synergistic interactions between intrinsic and extrinsic signals. Subtypes of adult mammalian stem cells can be maintained in this poised, quiescent state, and subsequently reactivated upon tissue injury to restore homeostasis. However, quiescence can become deregulated in pathological settings. In this review, we discuss the recent advances uncovering intracellular signaling pathways, transcriptional changes, and extracellular cues within the stem cell niche that control induction and exit from quiescence in tissue stem cells. We discuss the implications of quiescence as well as the pharmacological and genetic approaches that are being explored to either induce or prevent quiescence as a therapeutic strategy.

Fibro-adipogenic progenitors of dystrophic mice are insensitive to NOTCH regulation of adipogenesis

Fibro-adipogenic progenitors (FAPs) promote satellite cell differentiation in adult skeletal muscle regeneration. However, in pathological conditions, FAPs are responsible for fibrosis and fatty infiltrations. Here we show that the NOTCH pathway negatively modulates FAP differentiation both in vitro and in vivo. However, FAPs isolated from young dystrophin-deficient mdx mice are insensitive to this control mechanism. An unbiased mass spectrometry-based proteomic analysis of FAPs from muscles of wild-type and mdx mice suggested that the synergistic cooperation between NOTCH and inflammatory signals controls FAP differentiation. Remarkably, we demonstrated that factors released by hematopoietic cells restore the sensitivity to NOTCH adipogenic inhibition in mdx FAPs. These results offer a basis for rationalizing pathological ectopic fat infiltrations in skeletal muscle and may suggest new therapeutic strategies to mitigate the detrimental effects of fat depositions in muscles of dystrophic patients.

Development and validation of RdRp Screen, a crystallization screen for viral RNA-dependent RNA polymerases

Members of the Flaviviridae family constitute a severe risk to human health. Whilst effective drugs have been developed against the hepacivirus HCV, no antiviral therapy is currently available for any other viruses, including the flaviviruses dengue (DENV), West Nile and Zika viruses. The RNA-dependent RNA polymerase (RdRp) is responsible for viral replication and represents an excellent therapeutic target with no homologue found in mammals. The identification of compounds targeting the RdRp of other flaviviruses is an active area of research. One of the main factors hampering further developments in the field is the difficulty in obtaining high-quality crystal information that could aid a structure-based drug discovery approach. To address this, we have developed a convenient and economical 96-well screening platform. We validated the screen by successfully obtaining crystals of both native DENV serotype 2 and 3 RdRps under several conditions included in the screen. In addition, we have obtained crystal structures of RdRp3 in complex with a previously identified fragment using both soaking and co-crystallization techniques. This work will streamline and accelerate the generation of crystal structures of viral RdRps and provide the community with a valuable tool to aid the development of structure-based antiviral design.

Summary: We have developed a 96-well crystallization screen for viral RNA-dependent RNA polymerases (RdRps). The screen provides a convenient platform for streamlining the crystallisation of RdRps and implementing structure-based drug discovery programs.

Management of unscheduled tetanus prophylaxis in Emergency Departments: Point-of-Care implementation as a rapid tool for the evaluation of anti-tetanus antibodies

Background and aim: Each analytical activity, including those carried out in Point of Care (POCT) must be, at law, under the control of Laboratory Medicine. Before the implementation of the rapid tetanus quick stick (TQS) test for the evaluation of the specific tetanus immunisation, a multi-disciplinary and multi-professional group was created. The aim of this study was to evaluate the ability of Emergency Department (ED) staff to manage and correctly understand the result of TQS test in POCT. <br />Materials and Methods: This analysis took into consideration 152 patients admitted to ED with traumatic wounds; information on the state of tetanus immunisation at their arrival wasn’t recorded. Blood sample analysis was performed twice. The Laboratory confirmed a 100% concordance between their results and ELISA test (standard criterion). Study design consisted of 2 phases: the first one (50 test) to preliminarily evaluate if any corrective action or improvement of procedures is required, and the second one (102 tests) to confirm the quality of corrective actions. <br />Results: The concordance of results between TQS test in Laboratory and POCT test in ED was 80% in the first phase and 95% in the second one.<br />Conclusions: The use of the rapid TQS test is a valuable tool; however, to avoid serious mistakes of interpretation, periodic checks on the quality of the results must be arranged.