[Artificial intelligence and secure use of health data in the KI-FDZ project: anonymization, synthetization, and secure processing of real-world data]. / Künstliche Intelligenz und sichere Gesundheitsdatennutzung im Projekt KI-FDZ: Anonymisierung, Synthetisierung und sichere Verarbeitung für Real-World-Daten.

The increasing digitization of the healthcare system is leading to a growing volume of health data. Leveraging this data beyond its initial collection purpose for secondary use can provide valuable insights into diagnostics, treatment processes, and the quality of care. The Health Data Lab (HDL) will provide infrastructure for this purpose. Both the protection of patient privacy and optimal analytical capabilities are of central importance in this context, and artificial intelligence (AI) provides two opportunities. First, it enables the analysis of large volumes of data with flexible models, which means that hidden correlations and patterns can be discovered. Second, synthetic - that is, artificial - data generated by AI can protect privacy.This paper describes the KI-FDZ project, which aims to investigate innovative technologies that can support the secure provision of health data for secondary research purposes. A multi-layered approach is investigated in which data-level measures can be combined in different ways with processing in secure environments. To this end, anonymization and synthetization methods, among others, are evaluated based on two concrete application examples. Moreover, it is examined how the creation of machine learning pipelines and the execution of AI algorithms can be supported in secure processing environments. Preliminary results indicate that this approach can achieve a high level of protection while maintaining data validity. The approach investigated in the project can be an important building block in the secure secondary use of health data.

Incidence of type 1 and type 2 diabetes before and during the COVID-19 pandemic in Germany: analysis of routine data from 2015 to 2021.

Background: To date, there is no data available depicting the trend of the incidence of type 1 and type 2 diabetes across all age groups for the COVID-19 pandemic years in Germany. Methods: Based on anonymized routine data from nine million persons covered by statutory health insurance, newly diagnosed diabetes cases (ICD diagnosis E10.- to E14.-) in inpatient or (confirmed in two quarters) outpatient setting were estimated for 2015 to 2021, differentiating between type 1 and type 2 diabetes. The data were linked to the German Index of Socioeconomic Deprivation. The results are age-standardised (population as of 31 Dec. 2021). Results: Between 2015 and 2021, the incidence of type 1 diabetes increased from 9.5 to 11.6 per 100,000 persons (from 7,007 to 8,699 new cases per year). In contrast, the incidence of type 2 diabetes tended to decline between 2015 and 2019. It continued to drop initially in 2020 during the pandemic, and then rose to 740 per 100,000 persons in 2021 (556,318 new cases per year). The diabetes type-specific seasonal pattern of previous years has changed during the pandemic years. The incidence of both type 1 and type 2 diabetes was observed to be higher in regions of high socioeconomic deprivation as compared to regions characterised by low socioeconomic deprivation. Conclusions: The increase in the incidence of type 1 and type 2 diabetes in 2021 may possibly be related to the COVID-19 pandemic. The high incidence and the differences by regional socioeconomic deprivation indicate that there is a need for targeted prevention strategies.

Routine practice data of three cancer entities: Comparison among cancer registry and health insurance data.

INTRODUCTION: Claims data and cancer registry data are valuable secondary data sources for addressing health service research questions. This study provides a thorough insight into the comparability of data from health insurance companies and cancer registries in Germany regarding breast, prostate, and lung cancer patients and their treatment. METHODS: For this study claims data of the InGef database and data of the Cancer Registry of Rhineland-Palatinate were used to identify patients living in Rhineland-Palatinate with an incident breast, prostate, or lung cancer diagnosis between Jan. 1, 2018 and Dec. 31, 2019. Both datasets were compared for patient and tumour characteristics as well as treatment strategy. For the descriptive analysis of tumour localisation and treatment all patients were followed up for a maximum of two years. RESULTS: A total of 1,470 incident cancer cases were identified in the InGef database and 1,694 in the Cancer Registry. Data on sex, age, and tumour localisation matched well for all cancer entities in the cohorts. Data for early UICC stages I+II varied between the cohorts for prostate cancer (84% InGef, 66% Cancer Registry) and lung cancer (29% InGef, 20% Cancer Registry). Larger deviations were found for antihormonal treatment (breast 54% vs. 44%, prostate 32% vs. 18%). Significant differences were found for surgery (breast and lung) and radiation (breast and prostate), respectively. DISCUSSION: Age at diagnosis, tumour localisation, and treatment for breast cancer was well documented in both databases. Tumour-specific deviations were observed for tumour localisations (lung cancer), UICC stage (prostate and lung cancer) and treatment options. CONCLUSION: Both databases show very good completeness across cancer entities, but at the same time have minor limitations where they could readily complement each other. Individual linkage of claims and registry data could be an important step to improve oncological studies with routine practice data and to overcome the limitations identified.

Machine learning-based identification of risk-factor signatures for undiagnosed atrial fibrillation in primary prevention and post-stroke in clinical practice.

AIMS: Atrial fibrillation (AF) carries a substantial risk of ischemic stroke and other complications, and estimates suggest that over a third of cases remain undiagnosed. AF detection is particularly pressing in stroke survivors. To tailor AF screening efforts, we explored German health claims data for routinely available predictors of incident AF in primary care and post-stroke using machine learning methods. METHODS AND RESULTS: We combined AF predictors in patients over 45 years of age using claims data in the InGef database (n = 1 476 391) for (i) incident AF and (ii) AF post-stroke, using machine learning techniques. Between 2013-2016, new-onset AF was diagnosed in 98 958 patients (6.7%). Published risk factors for AF including male sex, hypertension, heart failure, valvular heart disease, and chronic kidney disease were confirmed. Component-wise gradient boosting identified additional predictors for AF from ICD-codes available in ambulatory care. The area under the curve (AUC) of the final, condensed model consisting of 13 predictors, was 0.829 (95% confidence interval (CI) 0.826-0.833) in the internal validation, and 0.755 (95% CI 0.603-0.890) in a prospective validation cohort (n = 661). The AUC for post-stroke AF was of 0.67 (95% CI 0.651-0.689) in the internal validation data set, and 0.766 (95% CI 0.731-0.800) in the prospective clinical cohort. CONCLUSION: ICD-coded clinical variables selected by machine learning can improve the identification of patients at risk of newly diagnosed AF. Using this readily available, automatically coded information can target AF screening efforts to identify high-risk populations in primary care and stroke survivors.

Real-world anticoagulatory treatment after percutaneous mitral valve repair using MitraClip: a retrospective, observational study on 1300 patients.

AIMS: This study sought to investigate current anticoagulatory treatment patterns and clinical outcome in patients undergoing transcatheter mitral valve repair (MitraClip). METHODS AND RESULTS: In a retrospective study of a German claims database (InGef research database), anticoagulatory treatment regimens were assessed using any drug prescription post discharge within the first 90 days after MitraClip procedure. Clinical events between 30 days and 6 months were examined by treatment regime. The study population comprised 1342 patients undergoing MitraClip procedure between 2014 and 2018. 22.4% received antiplatelet monotherapy, 20.8% oral anticoagulation (OAC) plus antiplatelet therapy, 19.4% OAC monotherapy, 11.7% dual antiplatelet therapy, 2.8% triple therapy and 21.0% did not receive any anticoagulatory drugs. 63% of patients with OAC received non-vitamin-K antagonist oral anticoagulants (NOAC). A total of 168 patients were newly prescribed OAC after MitraClip, of whom 12 patients (7.1%) had no diagnosis of atrial fibrillation or venous thromboembolism. 40% of patients with OAC prior to MitraClip did not have any OAC after MitraClip. The adjusted risk of all-cause mortality was significantly increased in patients with no anticoagulatory treatment (HR 3.84, 95% CI 2.33-6.33, p < 0.0001) when compared to antiplatelet monotherapy whereas the other regimes were not significantly different. CONCLUSIONS: This large real-world data analysis demonstrates a heterogeneous spectrum of prescriptions for anticoagulant therapies after MitraClip. Considering relevant differences in clinical outcome across treatment groups, major effort is warranted for controlled trials in order to establish evidence-based recommendations on anticoagulatory treatment after percutaneous mitral valve repair.

Lung cancer patients' comorbidities and attendance of German ambulatory physicians in a 5-year cross-sectional study.

The majority of lung cancer patients are diagnosed with an advanced stage IV, which has short survival time. Many lung cancer patients have comorbidities, which influence treatment and patients' quality of life. The aim of the study is to describe comorbidities in incident lung cancer patients and explore their attendance of ambulatory care physicians in Germany. In the observed period, 13,111 persons were first diagnosed with lung cancer (1-year incidence of 36.4 per 100,000). The mean number of comorbidities over 4 quarters was 30.77 ± 13.18; mean Charlson Comorbidity Index was 6.66 ± 2.24. In Germany, ambulatory care physicians most attended were general practitioners (2.6 quarters with contact within 4 quarters). Lung cancer was diagnosed by a general practitioner in 38% of the 13,111 incident patients. The average number of ambulatory care physician contacts over 4 quarters was 35.82 ± 27.31. High numbers of comorbidities and contacts in ambulatory care are common in patients with lung cancer. Therefore, a cross-sectoral and interdisciplinary approach is required for effective, patient-centred care. This was a 5-year cross-sectoral study, based on the InGef research database, which covers anonymized health insurance data of 7.2 million individuals in Germany. Incident lung cancer patients in a 5-year period (2013-2017) were identified. Descriptive statistics were calculated for sociodemographic characteristics, comorbidities, and attendance of ambulatory care physicians.

Real-World Anticoagulatory Treatment After Transcatheter Aortic Valve Replacement: A Retrospective, Observational Study on 4,800 Patients.

Background: Transcatheter aortic valve replacement (TAVR) has developed to the therapy of choice for patients with symptomatic severe aortic stenosis who are unsuitable for surgical aortic valve replacement and elderly patients with intermediate or high operative risk. However, the optimal anticoagulant therapy post-TAVR still remains a matter of debate. Aims: This study sought to investigate current anticoagulant treatment patterns and clinical outcome in patients undergoing TAVR. Methods: In a retrospective study based on anonymized health claims data of approximately seven million Germans with statutory health insurance (InGef database), anticoagulant treatment regimens were assessed using any drug prescription post discharge within the first 90 days after TAVR procedure. Clinical events between 30 days and 6 months were examined by treatment regime. Results: The study population comprised 4,812 patients with TAVR between 2014 and 2018: 29.4% received antiplatelet monotherapy, 17.8% dual antiplatelet therapy, 17.4% oral anticoagulation (OAC) plus antiplatelet therapy, 12.9% OAC monotherapy, 2.2% triple therapy and 19.2% did not receive any anticoagulatory drugs. Sixty-four percentage of patients with OAC received direct oral anticoagulants (DOAC). Hence, 68% of all patients were treated non-adherent to current guidelines. Forty percentage of patients with OAC prior to TAVR did not have any OAC after TAVR. The adjusted risk of all-cause mortality was significantly increased in patients with OAC (HR 1.40, 95% CI 1.03-1.90, p = 0.03) and no anticoagulatory treatment (HR 3.95, 95% CI 2.95-5.27, p < 0.0001) when compared to antiplatelet monotherapy. Conclusions: This large real-world data analysis demonstrates substantial deviations from guideline recommendations and treatment after TAVR. Considering relevant differences in clinical outcome across treatment groups, major effort is warranted to examine underlying causes and improve guideline adherence.

Clinical outcomes and characteristics of patients hospitalized for Influenza or COVID-19 in Germany.

OBJECTIVES: Since the beginning of the severe acute respiratory syndrome coronavirus 2 pandemic, there is a discussion about the severity of coronavirus disease-2019 (COVID-19) in comparison to infections with seasonal Influenza. The objective of this study was to compare clinical and demographic characteristics of German patients hospitalized for infection with either SARS-CoV-2 or Influenza. METHODS: This study used anonymized German healthcare claims data. Patients with a confirmed COVID-19 or Influenza diagnosis, for whom a complete hospital course was available (i.e., the patient was discharged or died in hospital) were included. The data set included detailed information on patient characteristics and hospital treatment. Patients were grouped according to whether they were transferred to the intensive care unit (ICU), received mechanical ventilation (MV), or had a severe course of the disease (SD). Charlson Comorbidity Index in the eight quarters prior to hospitalization and secondary diagnoses during hospitalization were analyzed. RESULTS: A total of 2343 hospitalized patients with COVID-19 and 6762 hospitalized patients with Influenza were included. Fifty-four percent of the patients were male patients, with men being twice as frequent in the COVID-19 severe groups. For both diseases, patients >49 years accounted for almost three-quarters of hospital cases and hypertension, diabetes mellitus, chronic kidney disease, and chronic obstructive pulmonary disease were the most common comorbidities. The proportion of cases with ICU, MV, and SD was substantially higher for patients with COVID-19 (ICU+: 21 vs. 13 %; MV+: 15 vs. 9%; and SD+: 28 vs. 16%). Overall inhospital mortality was more than two-fold higher in COVID-19 vs. Influenza (14 vs. 6%).). The length of ventilation and hospitalization, and the proportion of patients diagnosed with acute respiratory distress syndrome, systemic inflammatory response syndrome, or acute kidney injury were considerably higher in patients with COVID-19. CONCLUSIONS: COVID-19 resulted in higher inhospital mortality and worse clinical outcomes than Influenza. This was not attributable to demographic characteristics, preexisting comorbidities, or patient triage, because the German healthcare system had not reached its limits in the pandemic. Discussions suggesting that COVID-19 and seasonal Influenza have similar severity cannot be based on clinical evidence.

Short-Time Ocular Ischemia Induces Vascular Endothelial Dysfunction and Ganglion Cell Loss in the Pig Retina.

Visual impairment and blindness are often caused by retinal ischemia-reperfusion (I/R) injury. We aimed to characterize a new model of I/R in pigs, in which the intraocular pathways were not manipulated by invasive methods on the ocular system. After 12 min of ischemia followed by 20 h of reperfusion, reactivity of retinal arterioles was measured in vitro by video microscopy. Dihydroethidium (DHE) staining, qPCR, immunohistochemistry, quantification of neurons in the retinal ganglion cell layer, and histological examination was performed. Retinal arterioles of I/R-treated pigs displayed marked attenuation in response to the endothelium-dependent vasodilator, bradykinin, compared to sham-treated pigs. DHE staining intensity and messenger RNA levels for HIF-1α, VEGF-A, NOX2, and iNOS were elevated in retinal arterioles following I/R. Immunoreactivity to HIF-1α, VEGF-A, NOX2, and iNOS was enhanced in retinal arteriole endothelium after I/R. Moreover, I/R evoked a substantial decrease in Brn3a-positive retinal ganglion cells and noticeable retinal thickening. In conclusion, the results of the present study demonstrate that short-time ocular ischemia impairs endothelial function and integrity of retinal blood vessels and induces structural changes in the retina. HIF-1α, VEGF-A, iNOS, and NOX2-derived reactive oxygen species appear to be involved in the pathophysiology.

Responses of retinal arterioles and ciliary arteries in pigs with acute respiratory distress syndrome (ARDS).

Acute respiratory distress syndrome (ARDS) is a clinical syndrome of acute lung failure in critically sick patients, which severely compromises the function of multiple organs, including the brain. Although, the optic nerve and the retina are a part of the central nervous system, the effects of ARDS on these ocular structures are completely unknown. Thus, the major goal of this study was to test the hypothesis that ARDS affects vascular function in the eye. ARDS was induced in anesthetized pigs by intratracheal injection of lipopolysaccharide (LPS). Sham-treated animals served as controls. Pigs were monitored for 8 h and then sacrificed. Subsequently, retinal arterioles and short posterior ciliary arteries were isolated and cannulated with micropipettes to measure vascular responses by videomicroscopy. Levels of reactive oxygen species (ROS) were quantified in isolated vessels using dihydroethidium (DHE). Messenger RNA expression of hypoxic, inflammatory, prooxidative, and antioxidative genes was assessed by real-time PCR. When group-dependent differences in mRNA expression levels were found for a particular gene, immunostainings were conducted. Strikingly, responses to the endothelium-dependent vasodilator, bradykinin, were markedly impaired in retinal arterioles of LPS-treated pigs, but no differences were seen between ciliary arteries of LPS- and sham-treated animals. ROS levels were increased in retinal arterioles but not in ciliary arteries of LPS-treated pigs. Messenger RNA levels for HIF-1α, VEGF-A and NOX2 were markedly increased in retinal arterioles of LPS-treated pigs, whereas ciliary arteries had only negligible mRNA level changes. Pronounced immunoreactivity for HIF-1α, VEGF-A and NOX2 was seen in the endothelium of retinal arterioles from LPS-treated pigs. Histologically, massive edema was seen especially in the retinal nerve fiber layer of pigs treated with LPS. Our study provides the first evidence that ARDS induced by intratracheal LPS application evokes endothelial dysfunction in porcine retinal arterioles together with retinal edema, indicative of vascular leakage. In contrast, ciliary arteries appear to be resistant to intratracheal LPS application.

Hypoxia/Reoxygenation of Rat Renal Arteries Impairs Vasorelaxation via Modulation of Endothelium-Independent sGC/cGMP/PKG Signaling.

Ischemia/reperfusion injury holds a key position in many pathological conditions such as acute kidney injury and in the transition to chronic stages of renal damage. We hypothesized that besides a reported disproportional activation of vasoconstrictor response, hypoxia/reoxygenation (H/R) adversely affects endothelial dilatory systems and impairs relaxation in renal arteries. Rat renal interlobar arteries were studied under isometric conditions. Hypoxia was induced by application of 95% N2, 5% CO2 for 60 min to the bath solution, followed by a 10 min period of reoxygenation (95% O2, 5% CO2). The effect of H/R on relaxation was assessed using various inhibitors of endothelial dilatory systems. mRNA expression of phosphodiesterase 5 (PDE5), NADPH oxidases (NOX), and nitric oxide synthase (NOS) isoforms were determined using qRT-PCR; cGMP was assayed with direct cGMP ELISA. Acetylcholine induced relaxation was impaired after H/R. Inhibition of the NOS isoforms with L-NAME, and cyclooxygenases (COXs) by indomethacin did not abolish the H/R effect. Moreover, blocking the calcium activated potassium channels KCa3.1 and KCa2.1, the main mediators of the endothelium-derived hyperpolarizing factor, with TRAM34 and UCL1684, respectively, showed similar effects in H/R and control. Arterial stiffness did not differ comparing H/R with controls, indicating no impact of H/R on passive vessel properties. Moreover, superoxide was not responsible for the observed H/R effect. Remarkably, H/R attenuated the endothelium-independent relaxation by sodium nitroprusside, suggesting endothelium-independent mechanisms of H/R action. Investigating the signaling downstream of NO revealed significantly decreased cGMP and impaired relaxation during PDE5 inhibition with sildenafil after H/R. Inhibition of PKG, the target of cGMP, did not normalize SNP-induced relaxation following H/R. However, the soluble guanylyl cyclase (sGC) inhibitor ODQ abolished the H/R effect on relaxation. The mRNA expressions of the endothelial and the inducible NOS were reduced. NOX and PDE5 mRNA were similarly expressed in H/R and control. Our results provide new evidence that impaired renal artery relaxation after H/R is due to a dysregulation of sGC leading to decreased cGMP levels. The presented mechanism might contribute to an insufficient renal reperfusion after ischemia and should be considered in its pathophysiology.

Intramyocardial angiogenetic stem cells and epicardial erythropoietin save the acute ischemic heart.

Ischemic heart failure is the leading cause of mortality worldwide. An early boost of intracardiac regenerative key mechanisms and angiogenetic niche signaling in cardiac mesenchymal stem cells (MSCs) could improve myocardial infarction (MI) healing. Epicardial erythropoietin (EPO; 300 U kg-1) was compared with intraperitoneal and intramyocardial EPO treatments after acute MI in rats (n=156). Real-time PCR and confocal microscopy revealed that epicardial EPO treatment enhanced levels of intracardiac regenerative key indicators (SDF-1, CXCR4, CD34, Bcl-2, cyclin D1, Cdc2 and MMP2), induced transforming growth factor ß (TGF-ß)/WNT signaling in intramyocardial MSC niches through the direct activation of AKT and upregulation of upstream signals FOS and Fzd7, and augmented intracardiac mesenchymal proliferation 24 h after MI. Cardiac catheterization and tissue analysis showed superior cardiac functions, beneficial remodeling and increased capillary density 6 weeks after MI. Concomitant fluorescence-activated cell sorting, co-cultures with neonatal cardiomyocytes, angiogenesis assays, ELISA, western blotting and RAMAN spectroscopy demonstrated that EPO could promote cardiomyogenic differentiation that was specific of tissue origin and enhance paracrine angiogenetic activity in cardiac CD45-CD44+DDR2+ MSCs. Epicardial EPO delivery might be the optimal route for efficient upregulation of regenerative key signals after acute MI. Early EPO-mediated stimulation of mesenchymal proliferation, synergistic angiogenesis with cardiac MSCs and direct induction of TGF-ß/WNT signaling in intramyocardial cardiac MSCs could initiate an accelerated healing process that enhances cardiac recovery.

Hypoxia-reoxygenation enhances murine afferent arteriolar vasoconstriction by angiotensin II.

We tested the hypothesis that hypoxia-reoxygenation (H/R) augments vasoreactivity to angiotensin II (ANG II). In particular, we compared an in situ live kidney slice model with isolated afferent arterioles (C57Bl6 mice) to assess the impact of tubules on microvessel response. Hematoxylin and eosin staining was used to estimate slice viability. Arterioles in the slices were located by differential interference contrast microscopy, and responses to vasoactive substances were assessed. Cytosolic calcium transients and NADPH oxidase (NOX) mRNA expression were studied in isolated afferent arterioles. SOD activity was measured in live slices. Both experimental models were subjected to control and H/R treatment (60 min). Slices were further analyzed after 30-, 60-, and 90-min hypoxia followed by 10- or 20-min reoxygenation (H/R). H/R resulted in enhanced necrotic tissue damage compared with control conditions. To characterize the slice model, we applied ANG II (10-7 M), norepinephrine (NE; 10-5 M), endothelin-1 (ET-1; 10-7 M), and ATP (10-4 M), reducing the initial diameter to 44.5 ± 2.8, 50.0 ± 2.2, 45.3 ± 2.6, and 74.1 ± 1.8%, respectively. H/R significantly increased the ANG II response compared with control in live slices and in isolated afferent arterioles, although calcium transients remained similar. TEMPOL incubation prevented the H/R effect on ANG II responses. H/R significantly increased NOX2 mRNA expression in isolated arterioles. SOD activity was significantly decreased after H/R. Enhanced arteriolar responses after H/R occurred independently from the surrounding tissue, indicating no influence of tubules on vascular function in this model. The mechanism of increased ANG II response after H/R might be increased oxidative stress and increased calcium sensitivity of the contractile apparatus.

Cardiac Mesenchymal Stem Cells Proliferate Early in the Ischemic Heart.

BACKGROUND/PURPOSE: Cardiac mesenchymal stem cells (MSCs) could stimulate cell-specific regenerative mechanisms after myocardial infarction (MI) depending on spatial origin, distribution, and niche regulation. We aimed at identifying and isolating tissue-specific cardiac MSCs that could contribute to regeneration. METHODS: Following permanent ligation of the left anterior descending coronary artery in rats (n = 16), early cardiac tissues and cardiac mononuclear cells (MNCs) were analyzed by immunohistology, confocal laser scanning microscopy, and flow cytometry, respectively. Early postischemic specific MSCs were purified by fluorescence-activated cell sorting, cultivated under standardized culture conditions, and tested for multipotent differentiation in functional identification kits. RESULTS: Cardiac MSC niches were detected intramyocardially in cell clusters after MI and characterized by positive expression for vimentin, CD29, CD44, CD90, CD105, PDGFRα, and DDR2. Following myocardial ischemia, proliferation was induced early and proliferation density was approximately 11% in intramyocardial MSC clusters of the peri-infarction border zone. Cluster sizes increased by 157 and 64% in the peri-infarction and noninfarcted areas of infarcted hearts compared with noninfarcted hearts 24 h following MI, respectively. Coincidentally, flow cytometry analyses illustrated postischemic moderate enrichments of CD45-CD44+ and CD45-DDR2+ cardiac MNCs. We enabled isolation of early postischemic culturable cardiac CD45-CD44+DDR2+ MSCs that demonstrated typical clonogenicity with colony-forming unit-fibroblast formation as well as adipogenic, chondrogenic, and osteogenic differentiation. CONCLUSIONS: MI triggered early proliferation in specific cardiac MSC niches that were organized in intramyocardial clusters. Following targeted isolation, early postischemic cardiac CD45-CD44+DDR2+ MSCs exhibited typical characteristics with multipotent differentiation capacity and clonogenic expansion.

Short-term hypoxia and vasa recta function in kidney slices.

BACKGROUND: Descending vasa recta (DVR) supply the inner part of outer renal medulla an area at risk for hypoxic damages. OBJECTIVE: We hypothesize increased vasoreactivity after hypoxia/re-oxygenation (H/R) in DVR, which might contribute to the reduced medullary perfusion after an ischemic event. METHODS: Live kidney slices (200µm) from SD rats were used for functional experiments. TUNEL assay and H&E staining were used to estimate slice viability. Kidney slices were treated with carbogen or hypoxia (1% O2) for 60 or 90 min and vasoreactivity to Ang II (10-7 M) was recorded by DIC microscopy after re-oxygenation with carbogen. Expression of NOS and NADPH enzymes mRNA were determined in iron-perfusion isolated VR. RESULTS: Percentage of apoptotic cells increased in control and H/R after 90 min in the medulla. Ang II- induced constriction of DVR was reduced after 90 min in control (compared to 60 min), but not after H/R. NOS enzymes mRNA expression levels decreased over 90 min hypoxia. CONCLUSIONS: Increased reactivity of DVR to Ang II after H/R compared to control (90 min) suggest a role of DVR in renal ischemia/reperfusion injury.

Exploiting AT2R to Improve CD117 Stem Cell Function In Vitro and In Vivo--Perspectives for Cardiac Stem Cell Therapy.

BACKGROUND/AIMS: CD117(+) stem cell (SC) based therapy is considered an alternative therapeutic option for terminal heart disease. However, controversies exist on the effects of CD117(+) SC implantation. In particular, the link between CD117(+) SC function and angiotensin-II-type-2 receptor (AT2R) after MI is continuously discussed. We therefore asked whether 1) AT2R stimulation influences CD117(+) SC properties in vitro and, 2) which effects can be ascribed to AT2R stimulation in vivo. METHODS: We approached AT2R stimulation with Angiotensin II while simultaneously blocking its opponent receptor AT1 with Losartan. CD117 effects were dissected using a 2D-Matrigel assay and HL-1 co-culture in vitro. A model of myocardial infarction, in which we implanted EGFP(+) CD117 SC, was further applied. RESULTS: While we found indications for AT2R driven vasculogenesis in vitro, co-culture experiments revealed that CD117(+) SC improve vitality of cardiomyocytes independently of AT2R function. Likewise, untreated CD117(+) SC had a positive effect on cardiac function and acted cardioprotective in vivo. CONCLUSIONS: Therefore, our data show that transient AT2R stimulation does not significantly add to the beneficial actions of CD117(+) SC in vivo. Yet, exploiting AT2R driven vasculogenis via an optimized AT2R stimulation protocol may become a promising tool for cardiac SC therapy.

The CD4(+) AT2R(+) T cell subpopulation improves post-infarction remodelling and restores cardiac function.

Myocardial infarction (MI) is a major condition causing heart failure (HF). After MI, the renin angiotensin system (RAS) and its signalling octapeptide angiotensin II (Ang II) interferes with cardiac injury/repair via the AT1 and AT2 receptors (AT1R, AT2R). Our study aimed at deciphering the mechanisms underlying the link between RAS and cellular components of the immune response relying on a rodent model of HF as well as HF patients. Flow cytometric analyses showed an increase in the expression of CD4(+) AT2R(+) cells in the rat heart and spleen post-infarction, but a reduction in the peripheral blood. The latter was also observed in HF patients. The frequency of rat CD4(+) AT2R(+) T cells in circulating blood, post-infarcted heart and spleen represented 3.8 ± 0.4%, 23.2 ± 2.7% and 22.6 ± 2.6% of the CD4(+) cells. CD4(+) AT2R(+) T cells within blood CD4(+) T cells were reduced from 2.6 ± 0.2% in healthy controls to 1.7 ± 0.4% in patients. Moreover, we characterized CD4(+) AT2R(+) T cells which expressed regulatory FoxP3, secreted interleukin-10 and other inflammatory-related cytokines. Furthermore, intramyocardial injection of MI-induced splenic CD4(+) AT2R(+) T cells into recipient rats with MI led to reduced infarct size and improved cardiac performance. We defined CD4(+) AT2R(+) cells as a T cell subset improving heart function post-MI corresponding with reduced infarction size in a rat MI-model. Our results indicate CD4(+) AT2R(+) cells as a promising population for regenerative therapy, via myocardial transplantation, pharmacological AT2R activation or a combination thereof.

OATP1A/1B transporters affect irinotecan and SN-38 pharmacokinetics and carboxylesterase expression in knockout and humanized transgenic mice.

Organic anion-transporting polypeptides (OATP) mediate the hepatic uptake of many drugs, thus codetermining their clearance. Impaired hepatic clearance due to low-activity polymorphisms in human OATP1B1 may increase systemic exposure to SN-38, the active and toxic metabolite of the anticancer prodrug irinotecan. We investigated the pharmacokinetics and toxicity of irinotecan and SN-38 in Oatp1a/1b-null mice: Plasma exposure of irinotecan and SN-38 was increased 2 to 3-fold after irinotecan dosing (10 mg/kg, i.v.) compared with wild-type mice. Also, liver-to-plasma ratios were significantly reduced, suggesting impaired hepatic uptake of both compounds. After 6 daily doses of irinotecan, Oatp1a/1b-null mice suffered from increased toxicity. However, Oatp1a/1b-null mice had increased levels of carboxylesterase (Ces) enzymes, which caused higher conversion of irinotecan to SN-38 in plasma, potentially complicating pharmacokinetic analyses. Ces inhibitors blocked this increased conversion. Interestingly, liver-specific humanized OATP1B1 and OATP1B3 transgenic mice had normalized hepatic expression of Ces1 genes. While irinotecan liver-to-plasma ratios in these humanized mice were similar to those in Oatp1a/1b-null mice, SN-38 liver-to-plasma ratios returned to wild-type levels, suggesting that human OATP1B proteins mediate SN-38, but not irinotecan uptake in vivo. Upon direct administration of SN-38 (1 mg/kg, i.v.), Oatp1a/1b-null mice had increased SN-38 plasma levels, lower liver concentrations, and decreased cumulative biliary excretion of SN-38. Mouse Oatp1a/1b transporters have a role in the plasma clearance of irinotecan and SN-38, whereas human OATP1B transporters may only affect SN-38 disposition. Oatp1a/1b-null mice have increased expression and activity of Ces1 enzymes, whereas humanized mice provide a rescue of this phenotype.