Emergent ecology in a microscale model of the surface ocean

Microbial processes operate at the microscale, which is not resolved by existing ecosystem models. Here, we present a novel model that simulates a 1 mL three-dimensional cube using a hybrid Lagrangian-Eulerian approach, at ecologically relevant timescales. The model simulates individual microbes, including three phytoplankton size classes with healthy, senescent, and dead lifecycle stages; copiotrophic and oligotrophic heterotrophic bacteria; and dissolved organic matter at 50 µm resolution. Diffusion, shear, sedimentation, chemotaxis, and attachment processes are explicitly resolved. The emerging quantitative representation of the ecosystem shows that (1) copiotrophs grow mostly attached to eukaryotic phytoplankters and get almost all of their carbon from them vs. oligotrophs that grow on exudates and lysates of cyanobacteria; (2) contrasting diel patterns in substrate appearance in the phycosphere vs. ambient water and growth of particle-associated copiotrophs vs. free-living oligotrophs; (3) attached bacteria reduce carbon flux from the phycosphere, lowering chemotactic efficiency toward eukaryotes below that toward cyanobacteria; (4) shear reduces chemotactic efficiency and fitness of the copiotroph; and (5) the main benefit of chemotaxis is to locate attachment partners. These patterns are consistent with available observations. Our study provides insights into the microscale ecology of marine bacteria, and the open-source code is a tool for further research in this area.IMPORTANCEA large amount of global CO2 fixation is performed by marine phytoplankton, and a substantial fraction of that is released as dissolved organic carbon and further processed by heterotrophic bacteria. The interaction between phytoplankton and bacteria, i.e., the carbon flux between them, is therefore an important process in the global carbon and climate system. Some bacteria have developed specialized behavioral traits, like swimming and attachment, to increase their carbon acquisition. These interactions occur at the micrometer scale, for example, the immediate vicinity of phytoplankters (the phycosphere), but existing biogeochemical models typically only simulate down to the 1 meter vertical or ~100 kilometer horizontal scale. We present a new microscale model and use it to predict fluxes and other features in the surface ocean. The model makes important predictions about the fluxes between various types of phytoplankton and bacteria and the role of behavioral traits, and it provides a basis and tool for further research in this area.

[Acceptance of psychosocial bridging measures in dementia : Treatment observation during the COVID-19 pandemic]

BACKGROUND

In the event of a COVID-19-related absence from an outpatient treatment program, patients suffering from dementia and their caregivers were offered support from a distance. The aim was to examine the extent of the participants' burden as well as how the offer was accepted and evaluated.

MATERIAL AND METHODS

All participants (n = 63) were offered supportive telephone contact over a period of 8 weeks at varying frequencies (weekly, fortnightly). In addition patients received cognitive and physical tasks by mail every 2 weeks. In order to examine the acceptance of the support, data collected from clinical routine were included in a treatment observation. Additionally, all participants were asked to evaluate the support retrospectively.

RESULTS

Out of 63 contacted participants, 45 were included in the treatment observation. The telephone support was very well accepted and a tendency towards higher agreement could be ascertained by caregivers. The experience of burden remained stable at a moderate level for all participants; however, caregivers were significantly more burdened.

CONCLUSION

The present treatment observation shows the acceptance of a location-independent psychosocial treatment program for dementia for future pandemics or treatment failure as well as for the routine care, e.g. for patients with restricted mobility or those living in rural areas without direct hospital connection. In particular, our data strengthen the importance of programs for caregivers in order to alleviate their burden.

Factors associated with the closure of German obstetric units and its effects on accessibility

Background

An increase in regionalization of obstetric services is being observed worldwide. This study investigated factors associated with the closure of obstetric units in hospitals in Germany and aimed to examine the effect of obstetric unit closure on accessibility of obstetric care.

Methods

Secondary data of all German hospital sites with an obstetrics department were analyzed for 2014 and 2019. Multivariate logistic regression was performed to identify factors associated with obstetrics department closure. Subsequently, the driving times to a hospital site with an obstetrics department were mapped, and different scenarios resulting from further regionalization were modelled.

Results

Of 747 hospital sites with an obstetrics department in 2014, 85 obstetrics departments closed down by 2019. Only the annual number of live births was observed to be a factor significantly associated with the closure of obstetrics departments (odds ratio: 0·995; confidence interval: 0.993-0.997). Areas in which driving times to the next hospital site with an obstetrics department exceeded the 30 and 40 min threshold increased from 2014 to 2019. Scenarios in which only hospital sites with a pediatrics department or hospital sites with an annual birth volume of ≥ 600 were considered resulted in large areas in which the driving times would exceed the 30 and 40 min threshold.

Conclusions

The annual number of live births is a factor significantly associated with the closure of obstetrics departments. Despite the closure, good accessibility is maintained for most areas in Germany. Although further regionalization may ensure high-quality care and efficiency, it will have an impact on accessibility.

Key messages

• Despite the closure of many obstetric departments, regional accessibility to obstetric care remains good for most areas in Germany.

• Further regionalization may ensure high-quality care and efficiency but will have an impact on accessibility.

A German study on the impact of stress on interparental relationship strain after preterm birth

Background

Relationship satisfaction is an important predictor of well-being. Few studies address the effects of stress on interparental relationships of parents with preterm infants. However, the experience of a preterm birth represents an extreme, stressful event and therefore may place a strain on a relationship. Our aim is to examine the impact of postnatal stress on maternal and paternal perceptions of relationship strain.

Methods

As part of the Neo-CamCare project, a retrospective cross-sectional study was conducted targeting parents with infants with a birth weight below 1,500 g. Linear regression was used to analyse the influence of stress on relationship strain.

Results

437 mothers and 301 fathers participated. Data indicate that interparental relationship strain experienced by fathers (M = 2.61, SD = 1.46) is lower than strain experienced by mothers (M = 3.43, SD = 1.7). The stress level due to the infant's behaviour and appearance is lower in fathers (M = 2.53, SD = 0.95) than in mothers (M = 2.98, SD = 1.05). Stress due to parental role change is higher in mothers (M = 3.37, p = 1.04) than in fathers (M = 2.49, SD = 0.99). Regression analyses show that stress due to behaviour and appearance, as well as parental role change, can be associated with relationship strain in mothers. For fathers, only stress experienced due to the behaviour and appearance can be associated with relationship strain, whereas parental role change is not significant.

Conclusions

Our data illustrate that relationship strain can result from stress in mothers and fathers, indicating the need for stress prevention measures for both. Only mothers show relationship strain due to stress in their parental role. Although it is unclear what mechanisms underlie these findings, we assume that the maternal role is still primarily associated with child care. One way to relieve maternal stress could be to increase psychological support and the promotion paternal involvement in the postnatal period.

Key messages

Human, mouse scRNA-seq and flow cytometry data in ischemic heart failure models predict immune cell activation signatures with altered endothelial cell cross talk

 

Chronic ischemic Heart Failure (HF) with reduced ejection fraction is marked by adverse remodelling and sustained inflammation. The effects of monocytes and T cells in early state immune responses after myocardial infarction are known, to date their role in progression and maintenance of chronic HF remains elusive.

Single cell RNA sequencing of peripheral immune cells from healthy and HF donors revealed a significant increase of the antigen presentation (i.e. HLA-DRB5) and co-stimulatory molecules (i.e. ICAM-1) on monocytes, while the elevation of the T effector memory population in HF patients shows enhanced T cell activation. Subsequent flow cytometry validation in 55 healthy and 110 HF patients confirmed that HF derived monocytes have elevated levels of HLA-DRB5 predicts increased ICAM-1 and TREM-1 (p<0.0001 for both), indicating enhanced T cell activation capacity. In addition, the activated fraction of both CD4+ and CD8+ T cells, including central memory, effector memory and TEMRA cells, is significantly enriched in the HF patients (p<0.0001 for both) with reduction of the naïve T cells. T cell receptor (TCR) sequencing of age matched healthy and HF donors showed an increase in the relative TCR clonality in HF patients, indicating an expansion of the circulating T cells.

ScRNA-seq murine myocardial infarction (MI) time course data (day (d) 0/1/3/7/14/28/48 post-MI), found a progressive increase in Th17 cells and activated CD8+ T cells in the cardiac tissue at d48 (2.8x-, and 2.7x-fold, respectively) relative to d0. The T cell imbalance was marked by loss of immunosuppressive markers such as Lef1 (p=2e-30) in T cell clusters primarily populated by d48 relative to d0.

Mechanistically the downstream effects of the immune cell activation were analysed in the serum of HF patients, where increased levels of sICAM-1, IL-6 and TNFRI levels (1.75x-, 5.30x-, 2.63x-fold, respectively) could be detected. Furthermore, treatment of endothelial cells with the conditioning media from HF-immune cells induced capability to adhere with monocytes in a co-culture system but also decreased the checkpoint inhibitor molecule PD-L1, a known blocker of autoreactive T cells.

These data link HF with enhanced monocyte and T cell activation as well as T cell clonal expansion, along with increased T cell numbers in mouse hearts post-MI. These data suggest HF is may drive impaired resolution of inflammation in cardiac tissue and facilitate adverse remodelling and cardiac damage. Further studies will assess the specific role of chronic monocyte and T cell activation in the progression of heart failure.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DFG -Deutsche ForschungsgemeinschaftDZHK -Deutsches Zentrum für Herzkreislauferkrankungen

Suboptimal uptake, retention, and adherence of daily oral PrEP among people with OUD receiving HCV treatment

Background

Daily oral preexposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) prevents human immunodeficiency (HIV) among people who inject drugs (PWID). Despite rising HIV incidence and injection drug use (IDU), PrEP use remains low and there is limited research about uptake, adherence, and retention among PWID.

Methods

The ANCHOR investigation evaluated a community-based care model collocating hepatitis C virus (HCV) treatment, medication for opioid use disorder (OUD), and PrEP in individuals in Washington, DC, and Baltimore, Maryland. PrEP counseling was conducted from HCV treatment day 0 until week 24. Subjects could start any time during this window, were followed for 48 weeks, and were assessed for adherence by self-report and dried blood spot TDF analysis.

Results

One hundred ninety-eight participants were enrolled, of whom 185 (93%) were HIV negative. Twenty-nine individuals (15.7% of HIV-negative cohort) initiated PrEP. One hundred sixteen participants (62.7%) met 2014 Centers for Disease Control and Prevention (CDC) PrEP criteria due to IDU (82 [44.3%]), sex (9 [4.9%]), or both practices (25 [13.5%]). Providers recommended PrEP to 94 individuals (50.8%), and recommendation was associated with PrEP uptake. Median treatment duration was 104 days (interquartile range, 28–276 days), with 8 participants retained through week 48. Adherence was variable over time by self-report and declined by TDF analysis. No HIV seroconversions occurred.

Conclusions

This cohort of people with HCV and OUD experienced low uptake of PrEP despite the majority meeting CDC criteria. High rates of disruption and discontinuation, compounded by variable adherence, made TDF/FTC a suboptimal prevention strategy. Emerging modalities like long-acting formulations may address these barriers, but PWID have been excluded from their development to date.

Predictors of perceived pandemic preparedness among general practitioners

Background

General practitioners (GPs) are essential for providing and maintaining health care during a pandemic. Pandemic preparedness (PP) of GPs can play a vital role in their management of a pandemic situation. This study aimed to examine the association stockpiled personal protective equipment (PPE) and knowledge of pandemic plans on perceived PP among German GPs. This analysis is part of the research project COVID-GAMS (Funding code: 01KI2099).

Methods

Three multivariable linear regression models were developed based on an online cross-sectional survey for the period March-April 2020 (the onset of the pandemic in Germany). Data were collected using self-developed items on self-assessed PP and knowledge of a pandemic plan and its utility. The stock of seven PPE items was queried. For PPE items, three different PPE scores were compared. Control variables for all models were gender and age.

Results

508 GPs were included in the study; 65.16% believed that they were very poorly or poorly prepared. Furthermore, 13.83% of GPs were aware of a pandemic plan; 40% rated those plans as beneficial. The stock of FFP-2/3 masks, protective suits, face shields, safety glasses, and medical face masks were mostly considered completely insufficient or insufficient, whereas disposable gloves and disinfectants were considered sufficient or completely sufficient. The stock of PPE was significantly positively associated with PP and had the largest effect on PP across all models; the association of the knowledge of a pandemic plan was significant but considerably smaller. PPE scores did not vary considerably in their explanatory power. The assessment of a pandemic plan as beneficial did not significantly affect PP.

Conclusions

An adequate stockpile of PPE is essential for perceived pandemic preparedness among GPs. Pandemic plans are considered less important for GPs. General practitioners, health authorities, and policy makers should focus on stockpiling PPE for future pandemic emergencies.

Key messages

Sufficient stockpiled personal protective equipment is the most important factor influencing pandemic preparedness of general practitioners in Germany. Knowledge on a pandemic plan has a subordinate effect on pandemic preparedness of general practitioners; usefulness of a pandemic plan does not have a significant effect.

Patterns of cardiac involvement in patients with long COVID syndrome using cardiovascular magnetic resonance

Background

Long COVID (LC) is an increasingly recognized late complication of COVID-19 infection. Cardiovascular involvement has also been implicated, however, the type and extent of the underlying cardiovascular injury remains unknown.

Purpose

To evaluate the association between ongoing symptoms and findings with cardiovascular magnetic resonance (CMR) in consecutive patients recently recovered from COVID-19 illness.

Methods

Prospective observational cohort study of patients recently recovered from COVID-19 illness and no previously known cardiovascular disease were included between April 2020 and April 2021. Demographic characteristics, cardiac blood markers, and CMR imaging a minimum of 4 weeks from the diagnosis were obtained.

Results

Of the 389 included patients, 192 (49%) were male, the mean (±standard deviation) age was 44 (±13) years and 61 (16%) required hospitalization during the acute illness. The median (IQR) time interval between COVID-19 diagnosis and CMR was 94 (71–165) days. 298 (77%) of patients continued to experience ongoing cardiovascular symptoms (long COVID, LC), including dyspnea, palpitations, atypical chest pain and fatigue at the time of CMR at least 4 weeks after the infection. In most patients, the symptoms were only effort related 137 (46%), whereas in 98 (33%) the symptoms affected the activities of daily life; 10 (3%) had severe and debilitating symptoms at rest. Compared to those with no LC (NLC, n=91), LC patients were more commonly hospitalized, had significantly higher native T1, native T2, and showed pericardial enhancement and effusion (Figure 1). There were no differences in cardiac biomarkers, left ventricular (LV) and right ventricular ejection fraction and mass. Proportionally, men and women were similarly affected (n=144 (73%) vs. n=157 (80%), p=0.18). Previous hospitalization was associated with hypertension and ongoing detectable troponin. LC status was associated with previous hospitalization and CMR findings of raised native T1 and native T2, and in females also pericardial enhancement. Severity of symptoms were associated with increased native T1 and T2 and decreased end-diastolic volume, whereas cardiac function showed no significant difference.

Conclusions

In this cohort of patients recently recovered from COVID-19 infection, ongoing cardiovascular symptoms were common. The LC status was related to previous hospitalization and CMR imaging findings of myopericardial inflammation. The extent and type of cardiovascular findings was associated with the severity of symptoms. These findings indicate the need for ongoing investigation of the long-term cardiovascular consequences of COVID-19.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The German Heart Foundation (Deutsche Herzstiftung) and Bayer AG, Leverkusen, Germany

Chronic ischemic heart failure in humans is associated with changes in expression of antigen processing HLA types and activation of T-cells

Background

Sustained pathological inflammation is a hallmark of chronic ischemic heart failure (HF). The short term response to myocardial ischemia has found a protective phenotype for T regulatory cells, yet the extent and consequence of prolonged T-cell activation in chronic ischemic heart failure is unclear.

Methods and results

Single cell RNA sequencing of circulating immune cells (n=181,712 cells) from healthy (n=8) and heart failure donors (n=8) revealed a relative increase in the proportion of activated T cells in heart failure patients relative to healthy controls. T cell activation molecules of the HLA-DR series genes on antigen presenting cells were found to be strongly associated with heart failure patients in the sequencing data, with decreases in antigen processing genes (HLA-DM series) in heart failure patients. Validation via flow cytometry in 27 healthy controls and 43 heart failure patients showed relative decreases of greater than 30% for HLA-DM to HLA-DRB molecule ratios in HF patients (p=0.0082), suggesting an aberrant antigen presentation to T cells linked to autoimmunity in heart failure patients. Additionally, costimulatory molecules such as ICAM-1 (p=0.004) and activation markers like TREM-1 (p=0.04) were elevated in circulating monocytes cells, which may potentiate T cell activation. Correspondingly, a significant and striking decrease in CD4+ and CD8+ naïve T cells along with increases in combined effector memory and TEMRA cells could be evidenced in heart failure patients. Levels of the T-cell homing marker CCR5 were elevated in patients with heart failure. To gain additional insights into potential functional consequences in the heart, supernatants from 3h LPS stimulated immune cells (peripheral blood mononuclear cells or T cells) were applied to various vascular cell types (endothelial cells, pericytes) and with cardiac organoids for 48h. Apoptosis was increased more than 3 fold following incubation with media derived from peripheral blood cells of HF patients, suggesting that immune cells from heart failure patients can directly and indirectly impair cardiovascular cells.

Conclusion

Heart failure is marked by sustained increases in relative proportions of effector T cell and TEMRA populations and homing markers suggesting these cells may undergo extravasation to tissues and deteriorate inflamed myocardium - hastening heart failure progression, worsening prognosis. Further research is required to assess how these cells may migrate to myocardial tissues and what interventions could be useful for blocking myocardial damage.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): DZHK, DGK, SFB

Dynamic carbon flux network of a diverse marine microbial community

The functioning of microbial ecosystems has important consequences from global climate to human health, but quantitative mechanistic understanding remains elusive. The components of microbial ecosystems can now be observed at high resolution, but interactions still have to be inferred e.g., a time-series may show a bloom of bacteria X followed by virus Y suggesting they interact. Existing inference approaches are mostly empirical, like correlation networks, which are not mechanistically constrained and do not provide quantitative mass fluxes, and thus have limited utility. We developed an inference method, where a mechanistic model with hundreds of species and thousands of parameters is calibrated to time series data. The large scale, nonlinearity and feedbacks pose a challenging optimization problem, which is overcome using a novel procedure that mimics natural speciation or diversification e.g., stepwise increase of bacteria species. The method allows for curation using species-level information from e.g., physiological experiments or genome sequences. The product is a mass-balancing, mechanistically-constrained, quantitative representation of the ecosystem. We apply the method to characterize phytoplankton-heterotrophic bacteria interactions via dissolved organic matter in a marine system. The resulting model predicts quantitative fluxes for each interaction and time point (e.g., 0.16 µmolC/L/d of chrysolaminarin to Polaribacter on April 16, 2009). At the system level, the flux network shows a strong correlation between the abundance of bacteria species and their carbon flux during blooms, with copiotrophs being relatively more important than oligotrophs. However, oligotrophs, like SAR11, are unexpectedly high carbon processors for weeks into blooms, due to their higher biomass. The fraction of exudates (vs. grazing/death products) in the DOM pool decreases during blooms, and they are preferentially consumed by oligotrophs. In addition, functional similarity of phytoplankton i.e., what they produce, decouples their association with heterotrophs. The methodology is applicable to other microbial ecosystems, like human microbiome or wastewater treatment plants.

Photogrammetric evaluation of corrective surgery for trigonocephaly

The aim of this study was to capture preoperative, postoperative, and follow-up head shapes of male trigonocephaly patients who underwent fronto-orbital remodelling (FOR), using three-dimensional (3D) photography. Fifty-seven male infants with metopic synostosis operated on using standardized FOR during a 5-year period were included. All measurements were compared with those of an age-matched healthy control cohort (n = 253 for early postoperative comparison, n = 43 for the 1-year follow-up comparison) to determine the effect of FOR at 14 days and at 1 year post-surgery. Intracranial volume, frontal angle, nasofrontal angle, interfrontoparietal-interparietal ratio, and inter-orbital distances were measured 1 day preoperatively, 14 days and 1 year postoperatively. Mean age at surgery was 9.7 ± 1.1 months. Prior to surgery, boys with metopic synostosis showed a reduced intracranial volume (-7.0%, P < 0.001), frontal angle (-10.2%, P < 0.001), interfrontoparietal-interparietal ratio (-4.9%, P < 0.01), and orbital distances (-6.5%, P < 0.001) compared to the reference group, but values did not differ significantly from the specific control group after surgery (all P> 0.05). This was consistent by the time of the follow-up examination. Corrective surgery should therefore aim to achieve volume expansion and correction of the deformity. Furthermore, 3D photogrammetry provides a valuable alternative to computed tomography scans in the diagnosis of metopic synostosis, significantly reducing the amount of radiation exposure to the brain.

Subclinical tuberculosis and adverse infant outcomes in pregnant women with HIV

BACKGROUND: Tuberculosis (TB) in pregnant women with HIV is associated with adverse maternal and infant outcomes. Previous studies have described a substantial prevalence of subclinical TB in this group, but little is known about the impact of subclinical TB on maternal and pediatric outcomes.METHODS: The Tshepiso Study recruited 235 HIV-infected pregnant women with TB (and matched HIV-positive, TB-negative pregnant controls), in Soweto, South Africa, from 2011 to 2014. During enrolment screening, some women initially recruited as controls were subsequently diagnosed with prevalent TB. We therefore assessed the prevalence of subclinical TB, associated participant characteristics and outcomes.RESULTS: Of 162 women initially recruited as TB-negative controls, seven (4.3%) were found to have TB on sputum culture. All seven had negative WHO symptom screens, and six (86%) were smear-negative. Of their seven infants, one was diagnosed with TB, and three (43%) experienced complications compared to zero infants with TB and 11% experiencing complications in the control group of TB-negative mothers (P = 0.045).CONCLUSION: We discovered an appreciable prevalence of subclinical TB in HIV-infected pregnant women in Soweto, which had not been detected by screening algorithms based solely on symptoms. Infants of HIV-infected mothers with subclinical TB appear to have a higher risk of adverse outcomes than those of TB-negative mothers.

[A man with groin pain]

A 78-year-old man was evaluated at the outpatient orthopaedic clinic with progressive pain in the right groin. X-ray revealed osteoarthritis of the right hip and fibrous dysplasia of the proximal femur. Total hip arthroplasty was performed using a cemented long-stem femoral component spanning the entire lesion.

Advanced calibration kit for scanning microwave microscope: Design, fabrication, and measurement

We present in this paper a new design of a capacitive calibration kit for scanning microwave microscopy (SMM). As demonstrated by finite element modelings, the produced devices are highly independent of material parameters due to their lateral configuration. The fabrication of these gold-based structures is realized by using well established clean-room techniques. SMM measurements are performed under different conditions, and all capacitive structures exhibit a strong contrast with respect to the non-capacitive background. The obtained experimental data are employed to calibrate the used SMM tips and to extract the capacitance of produced devices following a method based on the short-open-load calibration algorithm for one-port vector network analyzers. The comparison of experimental capacitance and nominal values provided by our models proves the applicability of the used calibration approach for a wide frequency range.

Crystal structures of the selenoprotein glutathione peroxidase 4 in its apo form and in complex with the covalently bound inhibitor ML162

Wild-type human glutathione peroxidase 4 (GPX4) was co-expressed with SBP2 (selenocysteine insertion sequence-binding protein 2) in human HEK cells to achieve efficient production of this selenocysteine-containing enzyme on a preparative scale for structural biology. The protein was purified and crystallized, and the crystal structure of the wild-type form of GPX4 was determined at 1.0 Å resolution. The overall fold and the active site are conserved compared with previously determined crystal structures of mutated forms of GPX4. A mass-spectrometry-based approach was developed to monitor the reaction of the active-site selenocysteine Sec46 with covalent inhibitors. This, together with the introduction of a surface mutant (Cys66Ser), enabled the crystal structure determination of GPX4 in complex with the covalent inhibitor ML162 [(S)-enantiomer]. The mass-spectrometry-based approach described here opens the path to further co-complex crystal structures of this potential cancer drug target in complex with covalent inhibitors.

Metabolic activation and toxicological evaluation of polychlorinated biphenyls in Drosophila melanogaster

Degradation of polychlorinated biphenyls (PCBs) is initiated by cytochrome P450 (CYP) enzymes and includes PCB oxidation to OH-metabolites, which often display a higher toxicity than their parental compounds. In search of an animal model reflecting PCB metabolism and toxicity, we tested Drosophila melanogaster, a well-known model system for genetics and human disease. Feeding Drosophila with lower chlorinated (LC) PCB congeners 28, 52 or 101 resulted in the detection of a human-like pattern of respective OH-metabolites in fly lysates. Feeding flies high PCB 28 concentrations caused lethality. Thus we silenced selected CYPs via RNA interference and analyzed the effect on PCB 28-derived metabolite formation by assaying 3-OH-2',4,4'-trichlorobiphenyl (3-OHCB 28) and 3'-OH-4',4,6'-trichlorobiphenyl (3'-OHCB 28) in fly lysates. We identified several drosophila CYPs (dCYPs) whose knockdown reduced PCB 28-derived OH-metabolites and suppressed PCB 28 induced lethality including dCYP1A2. Following in vitro analysis using a liver-like CYP-cocktail, containing human orthologues of dCYP1A2, we confirm human CYP1A2 as a PCB 28 metabolizing enzyme. PCB 28-induced mortality in flies was accompanied by locomotor impairment, a common phenotype of neurodegenerative disorders. Along this line, we show PCB 28-initiated caspase activation in differentiated fly neurons. This suggested the loss of neurons through apoptosis. Our findings in flies are congruent with observation in human exposed to high PCB levels. In plasma samples of PCB exposed humans, levels of the neurofilament light chain increase after LC-PCB exposure, indicating neuronal damage. In summary our findings demonstrate parallels between Drosophila and the human systems with respect to CYP mediated metabolism and PCB mediated neurotoxicity.

Myocardial infarction triggers Inflammatory deterioration of vascular niche by accelerating loss of a specific vessel subtype in bone

Introduction

The interface between heart and bone emerges as a key trigger of post-infarction inflammation and progression of chronic heart failure (CHF). However, our knowledge on the underlying mechanisms of this interaction is incomplete. Bone vasculature, specifically so-called H-type (Endomucinhigh) endothelial cells (EC), plays a crucial role in maintenance of the bone integrity and regulation of hematopoietic stem cells (HSC). While previous studies in mice showed the reduction of H-type vessels by aging, the impact of ischemic heart disease is unclear. Therefore, we aimed to investigate the effects of myocardial infarction (MI) and chronic heart failure on the vascular bone cell composition in mice and humans.

Methods and results

Flow cytometric analysis of harvested bones at the different timepoints after MI induction in mice revealed a gradual loss of H-type endothelial cells in the time-course of developing chronic heart failure (P&lt;0.05 at day 7 and 14 vs. control; P&lt;0.0001 at day 28 vs. control). This results were confirmed in immunostainings of tibia sections showing a significant decrease of H-type vessel length after MI (p&lt;0.05 at day 14 and 28, accordingly). The loss of type-H endothelium was accompanied by a significant expansion of long-term HSC in the bone (P=0.0005 at day 28 post MI vs. control). Importantly, type H ECs were also significantly reduced in the bone of ischemic post-infarct HF patients (n=16) compared with control subjects (n=8; P=0.0003). To gain insights into the mechanisms underlying the changes in the vascular niche, we performed single cells RNA sequencing of human BM ECs. These studies confirmed the decrease in Emcnexpressing ECs in ischemic HF patients, which was accompanied by significantly increased expression of inflammatory genes, including IL1b (P&lt;0.0001). Inflammatory EC phenotypes and IL1b expression in HF could be further confirmed at protein level using cytospin immunostainings. Murine studies further revealed an early induction IL-1b specifically in H-type vessels already at day 1 after MI induction, which preceded the loss of H-type endothelium within the following 4 weeks. By inhibiting IL-1b production using a specific Nlrp3 inflammasome inhibitor (MCC950) we could observe a partial restoration of H-type EC frequencies (P=0.033) and a significant increase in H-type vessel length (p=0.035) at day 28 day after MI.

Conclusions

Our data show for the first time an impact of myocardial infarction and chronic heart failure on the bone marrow vasculature. These changes seem to be strongly associated with inflammatory response in H-type vessels, which precedes its loss after MI. Specifically, the induction of the inflammatory cytokine IL1b may contribute to the disturbed phenotype. This suggest that inhibition of IL1b (e.g. by canakinumab) be used as a novel strategy to prevent or reverse the deterioration of the vascular bone function in ischemic heart disease.

Funding Acknowledgement

Type of funding source: None

DNMT3A clonal hematopoiesis-driver mutations are associated with profound changes in monocyte and T cell signatures in humans with heart failure

Background

Clonal hematopoiesis (CH) driven by mutations of DNA methyltransferase 3a (DNMT3A) is associated with increased incidence of cardiovascular disease and poor prognosis of patients with chronic heart failure (HF) and aortic stenosis. Although experimental studies suggest that DNMT3A CH-driver mutations may enhance inflammation, specific signatures of inflammatory cells in humans are missing. Single-cell RNA-sequencing provides a novel opportunity to define subsets of immune cells mediating inflammation in humans.

Methods

Transcriptomic profiles of peripheral blood mononuclear cells were analysed in N=6 HF patients harboring DNMT3A CH-drived mutations and with HF and N=5 patients with HF and DNMT3A mutations by single-cell RNA-sequencing.

Results

Monocytes of HF patients carrying DNMT3A mutations demonstrated a significantly increased expression of inflammatory genes compared to monocytes derived from patients with HF without DNMT3A mutations. Among the specific up-regulated genes were the prototypic inflammatory interleukins (IL) IL1B, IL6, and IL8, the macrophage inflammatory proteins CCL3 and CCL4 as well as restin, which augments monocyte-endothelial adhesion. The classical monocyte subset of DNMT3A mutation carriers showed increased expression of immunoglobulin superfamily members CD80, CD300LB, and SIGLEC12, as well as the cell adhesion molecule CD58, all of which may be involved in monocyte-T cell interactions. DNMT3A mutation carriers were further characterized by increased expression of T cell receptor chains and Th1, Th17, CD8+ and Treg specific signatures.

Conclusions

This study demonstrates that circulating monocytes and T cells of HF patients harboring CHIP-driver mutations in DNMT3A exhibit a highly inflamed transcriptome, which may contribute to the aggravation of chronic heart failure.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The German Research Foundation (SFB834, Project B1), and the German Center for Cardiovascular Research (DZHK).