Viral presence and immunopathology in a kidney transplant recipient with fatal COVID-19: a clinical autopsy report

COVID-19 is of special concern to immunocompromised individuals, including organ transplant recipients. However, the exact implications of COVID-19 for the immunocompromised host remain unclear. Existing theories regarding this matter are controversial and mainly based on clinical observations. Here, the postmortem histopathology, immunopathology, and viral presence in various tissues of a kidney transplant recipient with COVID-19 were compared to those of 2 nontransplanted patients with COVID-19 matched for age, sex, length of intensive care unit stay, and admission period in the pandemic. None of the tissues of the kidney transplant recipient demonstrated the presence of SARS-CoV-2. In lung tissues of both controls, some samples showed viral positivity with high Ct values with quantitative reverse transcription polymerase chain reaction. The lungs of the kidney transplant recipient and controls demonstrated similar pathology, consisting of acute fibrinous and organizing pneumonia with thrombosis and an inflammatory response with T cells, B cells, and macrophages. The kidney allograft and control kidneys showed a similar pattern of interstitial lymphoplasmacytic infiltration. No myocarditis could be observed in the hearts of the kidney transplant recipient and controls, although all cases contained scattered lymphoplasmacytic infiltrates in the myocardium, pericardium, and atria. The brainstems of the kidney transplant recipient and controls showed a similar pattern of lymphocytic inflammation with microgliosis. This research report highlights the possibility that, based on the results obtained from this single case, at time of death, the immune response in kidney transplant recipients with long-term antirejection immunosuppression use prior to severe illness is similar to nontransplanted deceased COVID-19 patients.

Serum T50 predicts cardiovascular mortality in individuals with type 2 diabetes: A prospective cohort study

BACKGROUND AND AIMS

Individuals with type 2 diabetes (T2D) have a higher risk of cardiovascular disease, compared with those without T2D. The serum T50 test captures the transformation time of calciprotein particles in serum. We aimed to assess whether serum T50 predicts cardiovascular mortality in T2D patients, independent of traditional risk factors.

METHODS

We analyzed 621 individuals with T2D in this prospective cohort study. Cox regression models were performed to test the association between serum T50 and cardiovascular and all-cause mortality. Causes of death were categorized according to ICD-10 codes. Risk prediction improvement was assessed by comparing Harrell's C for models without and with T50. RESULTS: The mean age was 64.2 ± 9.8 years, and 61% were male. The average serum T50 time was 323 ± 63 min. Higher age, alcohol use, high-sensitive C-reactive protein, and plasma phosphate were associated with lower serum T50 levels. Higher plasma triglycerides, venous bicarbonate, sodium, magnesium, and alanine aminotransferase were associated with higher serum T50 levels. After a follow-up of 7.5[5.4-10.7] years, each 60 min decrease in serum T50 was associated with an increased risk of cardiovascular (fully adjusted HR 1.32, 95% CI 1.08-1.50, and p = 0.01) and all-cause mortality (HR 1.15, 95%CI 1.00-1.38, and p = 0.04). Results were consistent in sensitivity analyses after exclusion of individuals with estimated glomerular filtration rate <45 or <60 mL/min/1.73 m2 and higher plasma phosphate levels.

CONCLUSIONS

Serum T50 improves prediction of cardiovascular and all-cause mortality risk in individuals with T2D. Serum T50 may be useful for risk stratification and to guide therapeutic strategies aiming to reduce cardiovascular mortality in T2D.

Plasma calprotectin and new-onset type 2 diabetes in the general population: a prospective cohort study

BACKGROUND

Systemic inflammation plays a pivotal role in the development of type 2 diabetes (T2D). Here we hypothesized that circulating levels of calprotectin, a myeloid cell-derived biomarker of inflammation, is associated with the development of new-onset T2D in the general population.

METHODS

A total of 4,815 initially non-diabetic participants of the Prevention of Renal and Vascular ENd-stage Disease (PREVEND), a prospective population-based cohort study, were assessed for plasma levels of calprotectin at baseline. Circulating levels of calprotectin were investigated for potential associations with the risk of new-onset T2D, defined as a fasting plasma glucose level ≥7.0 mmol/l, a random plasma glucose level ≥11.1 mmol/l, a self-reported physician-based diagnosis of T2D, the use of glucose-lowering drugs, or any combinations thereof.

RESULTS

Median plasma calprotectin levels were 0.49 [0.35-0.69] mg/l. Plasma calprotectin levels were significantly associated with the risk of new-onset T2D (hazard ratio [HR] per doubling 1.42 [95% confidence interval: 1.22-1.66], P<0.001). The association remained independent of adjustment for age and sex (HR 1.34 [95%CI: 1.14-1.57], P<0.001), but not after further adjustment for potentially confounding factors (HR 1.11 [95% CI: 0.90-1.37], P=0.326), with adjustment for hyperlipidemia and high-sensitivity C-reactive protein explaining the loss of significance. Stratified analyses showed significant effect modification by hypertension, history of cardiovascular disease and HOMA-IR (Pinteraction≤0.001 for each), with higher HRs in individuals without hypertension, without history of cardiovascular disease and with below-median HOMA-IR.

CONCLUSIONS

Elevated plasma levels of calprotectin are associated with a higher risk of developing T2D in the general population and may represent a moveable inflammatory biomarker. This association, however, does not represent a direct effect, and seems dependent on hyperlipidemia and systemic inflammation.

Systemic oxidative stress may be associated with reduced IgG antibody titers against SARS-CoV-2 in vaccinated kidney transplant recipients: A post-hoc analysis of the RECOVAC-IR observational study

BACKGROUND

Coronavirus disease 2019 (COVID-19) poses an increased risk for severe illness and suboptimal vaccination responses in patients with kidney disease, in which oxidative stress may be involved. Oxidative stress can be reliably measured by determining circulating free thiols (R-SH, sulfhydryl groups), since R-SH are rapidly oxidized by reactive species. In this study, we aimed to examine the association between serum free thiols and the ability to mount a humoral immune response to SARS-CoV-2 vaccination in kidney patients.

METHODS

Serum free thiol concentrations were measured in patients with chronic kidney disease stages 4/5 (CKD G4/5) (n = 46), on dialysis (n = 43), kidney transplant recipients (KTR) (n = 73), and controls (n = 50). Baseline serum free thiol and interferon-γ-induced protein-10 (IP-10) - a biomarker of the interferon response - were analyzed for associations with seroconversion rates and SARS-CoV-2 spike (S1)-specific IgG concentrations after two doses of the mRNA-1273 vaccine.

RESULTS

Albumin-adjusted serum free thiol concentrations were significantly lower in patients with CKD G4/5 (P < 0.001), on dialysis (P < 0.001), and KTR (P < 0.001), as compared to controls. Seroconversion rates after full vaccination were markedly reduced in KTR (52.1%) and were significantly associated with albumin-adjusted free thiols (OR = 1.76, P = 0.033). After adjustment for MMF use, hemoglobin, and eGFR, this significance was not sustained (OR = 1.49, P = 0.241).

CONCLUSIONS

KTR show suboptimal serological responses to SARS-CoV-2 vaccination, which is inversely associated with serum R-SH, reflecting systemic oxidative stress. Albeit this association was not robust to relevant confounding factors, it may at least partially be involved in the inability of KTR to generate a positive serological response after SARS-CoV-2 vaccination.

Serum peroxiredoxin-4, a biomarker of oxidative stress, is associated with the development of nephropathy in patients with type 2 diabetes (Zodiac-65)

Oxidative stress is implicated in the development and progression of type 2 diabetes (T2D). Peroxiredoxin-4 is an antioxidant protein, which may serve as biomarker of oxidative stress, and has previously been associated with new-onset T2D. In this study, we investigated associations between circulating peroxiredoxin-4 and the risk of developing new-onset microvascular complications in T2D patients. Serum peroxiredoxin-4 was measured in 536 patients with T2D with (n = 257) and without (n = 279) baseline microvascular complications who participated in a primary-care based cohort study (Zwolle Outpatient Diabetes project Integrating Available Care [ZODIAC] study). Over a median follow-up of 3.4 years, 38 (13.6%) developed nephropathy, defined as albuminuria in two consecutive urine samples. In multivariable Cox proportional hazards regression analyses, peroxiredoxin-4 was associated with new-onset nephropathy (hazard ratio [HR] per doubling 1.78 [95% CI: 1.27-2.49], P < 0.001) after adjustment for potential confounding factors, including age, sex, disease duration, HbA1c levels, macrovascular complications, systolic blood pressure, and even high-sensitive C-reactive protein. There was no interaction of peroxiredoxin-4 with hs-CRP impacting on new-onset nephropathy. No significant associations were found with new-onset retinopathy or neuropathy. In conclusion, circulating peroxiredoxin-4 associates positively with an increased risk of developing nephropathy in T2D independent and irrespective of low-grade inflammation.

Systemic Oxidative Stress in Severe Early-Onset Fetal Growth Restriction Associates with Concomitant Pre-Eclampsia, Not with Severity of Fetal Growth Restriction

BACKGROUND

Placental insufficiency is an important mechanism underlying early-onset fetal growth restriction (eoFGR). Reduced placental function causes impaired metabolic and gaseous exchange. This unfavorable placental environment is among other processes characterized by increased oxidative stress. Systemic free thiols (FT) are known for their reactive oxygen species scavenging capacity, and higher plasma levels of FT are associated with a better outcome in a multitude of ischemic and inflammatory diseases. We aimed to investigate the relationships between systemic FT levels and maternal and perinatal clinical characteristics and outcomes.

STUDY DESIGN

In a post hoc analysis of the Dutch Strider study, a cohort of women with eoFGR, we investigated the association between the maternal redox status (FT) levels at study inclusion, placental biomarkers, and maternal and neonatal outcomes in 108 patients.

RESULTS

FT were significantly lower in pregnancies complicated with eoFGR with concurrent maternal hypertensive disorders (pregnancy-induced hypertension; ρ = -0.281 p = 0.004, pre-eclampsia; ρ = -0.505 p = 0.000). In addition, lower FT levels were significantly associated with higher systolic (ρ = -0.348 p = 0.001) and diastolic blood pressure (ρ = -0.266 p = 0.014), but not with the severity of eoFGR. FT levels were inversely associated with sFlt (ρ = -0.366, p < 0.001). A strong relation between systemic FT levels and PlGF levels was observed in women with pre-eclampsia at delivery (ρ = 0.452, p = 0.002), which was not found in women without hypertensive disorders (ρ = 0.008, p = 0.958).

CONCLUSIONS

In women with pregnancies complicated with eoFGR, FT levels reflect the severity of maternal disease related to the underlying placental insufficiency rather than the severity of the placental dysfunction as reflected in eoFGR or perinatal outcomes.

Loss of Endothelial Glycocalyx During Normothermic Machine Perfusion of Porcine Kidneys Irrespective of Pressure and Hematocrit

Normothermic machine perfusion (NMP) is a promising modality for marginal donor kidneys. However, little is known about the effects of NMP on causing endothelial glycocalyx (eGC) injury. This study aims to evaluate the effects of NMP on eGC injury in marginal donor kidneys and whether this is affected by perfusion pressures and hematocrits.

Methods

Porcine slaughterhouse kidneys (n = 6/group) underwent 35 min of warm ischemia. Thereafter, the kidneys were preserved with oxygenated hypothermic machine perfusion for 3 h. Subsequently, 4 h of NMP was applied using pressure-controlled perfusion with an autologous blood-based solution containing either 12%, 24%, or 36% hematocrit. Pressures of 55, 75, and 95 mm Hg were applied in the 24% group. Perfusate, urine, and biopsy samples were collected to determine both injury and functional parameters.

Results

During NMP, hyaluronan levels in the perfusate increased significantly (P < 0.0001). In addition, the positivity of glyco-stained glycocalyx decreased significantly over time, both in the glomeruli (P = 0.024) and peritubular capillaries (P = 0.003). The number of endothelial cells did not change during NMP (P = 0.157), whereas glomerular endothelial expression of vascular endothelial growth factor receptor-2 decreased significantly (P < 0.001). Microthrombi formation was significantly increased after NMP. The use of different pressures and hematocrits did not affect functional parameters during perfusion.

Conclusions

NMP is accompanied with eGC and vascular endothelial growth factor receptor-2 loss, without significant loss of endothelial cells. eGC loss was not affected by the different pressures and hematocrits used. It remains unclear whether endothelial injury during NMP has harmful consequences for the transplanted kidney.

Severely increased albuminuria in patients with type 2 diabetes mellitus is associated with increased subclinical atherosclerosis in femoral arteries with Na [18F]F activity as a proxy - The DETERMINE study

BACKGROUND AND AIMS

Sodium [18F]fluoride (Na [18F]F) positron emission tomography imaging allows detailed visualization of early arterial micro-calcifications. This study aims to investigate atherosclerosis manifested by micro-calcification, macro-calcification, and aortic stiffness in patients with type 2 diabetes mellitus (T2DM) with and without albuminuria and severely decreased kidney function.

METHODS

A cohort was stratified in four groups (N = 10 per group), based on KDIGO categories (G1-5 A1-3). G1-2A1 non-diabetic controls (median [IQR] estimated glomerular filtration rate (eGFR) in mL/min/1.73 m2 91 [81-104]), G1-2A1 with T2DM (eGFR 87 [84-93], and albumin-creatinin-ratio (ACR) in mg/mmol 0.35 [0.25-0.75]), G1-2A3 with T2DM (eGFR 85 [60-103], and ACR 74 [62-122], and G4A3 with T2DM (eGFR 19 [13-27] and ACR 131 [59-304]).

RESULTS

Na [18F]F femoral artery grading score differed significantly in the groups with the highest Na [18F]F activity in A3 groups with T2DM (G1-2A3 with T2DM 228 [100-446] and G4A3 with T2DM 198 [113-578]) from the lowest groups of the G1-2A1 with T2DM (33 [0-93]) and in G1-2A1 non-diabetic controls (75 [0-200], p = 0.001). Aortic Na [18F]F activity and femoral artery computed tomography (CT)-assessed macro-calcification was increased in G4A3 with T2DM compared with G1-2A1 with T2DM (47.5 [33.8-73.8] vs. 17.5 [8.8-27.5] (p = 0.006) and 291 [170-511] vs. 12.2 [1.41-44.3] mg (p = 0.032), respectively). Carotid-femoral pulse wave velocity (PWV)-assessed aortic stiffness was significantly higher in both A3 groups with T2DM compared with G1-2A1 with T2DM (11.15 and 12.35 vs. 8.86 m/s, respectively (p = 0.009)).

CONCLUSIONS

This study indicates that the presence of severely increased albuminuria in patients with T2DM is cross-sectionally associated with subclinical arterial disease in terms of micro-calcification and aortic stiffness. Additional decrease in kidney function was associated with advanced macro-calcifications.

Calciprotein Particles Induce Endothelial Dysfunction by Impairing Endothelial Nitric Oxide Metabolism

BACKGROUND

Calciprotein particles (CPPs) are associated with the development of vascular calcifications in chronic kidney disease. The role of endothelial cells (ECs) in this process is unknown. Here, we investigated the interaction of CPPs and ECs, thereby focusing on endothelial nitric oxide metabolism and oxidative stress.

METHODS

CPPs were generated in calcium- and phosphate-enriched medium. Human umbilical vein endothelial cells were exposed to different concentrations of CPPs (0-100 µg/mL) for 24 or 72 hours. Ex vivo porcine coronary artery rings were used to measure endothelial cell-dependent vascular smooth muscle cell relaxation after CPP exposure. Serum samples from an early chronic kidney disease cohort (n=245) were analyzed for calcification propensity (measure for CPP formation) and nitrate and nitrite levels (NO_x).

RESULTS

CPP exposure for 24 hours reduced eNOS (endothelial nitric oxide synthase) mRNA expression and decreased nitrite production, indicating reduced nitric oxide bioavailability. Also, 24-hour CPP exposure caused increased mitochondria-derived superoxide generation, together with nitrotyrosine protein residue formation. Long-term (72 hours) exposure of human umbilical vein endothelial cells to CPPs induced eNOS uncoupling and decreased eNOS protein expression, indicating further impairment of the nitric oxide pathway. The ex vivo porcine coronary artery model showed a significant reduction in endothelial-dependent vascular smooth muscle cell relaxation after CPP exposure. A negative association was observed between NO_x levels and calcification propensity (r=-0.136; P=0.049) in sera of (early) chronic kidney disease patients.

CONCLUSIONS

CPPs cause endothelial cell dysfunction by impairing nitric oxide metabolism and generating oxidative stress. Our findings provide new evidence for direct effects of CPPs on ECs and pathways involved.

Validation of an ex vivo Flow Model Including Magnetic Resonance Imaging to Study the Effects of Endovascular Treatments on the Arterial Wall

Endovascular revascularization is the preferred treatment for peripheral arterial disease. Restenosis often occurs as a response to procedure-induced arterial damage. Reducing vascular injury during endovascular revascularization may improve its success rate. This study developed and validated an ex vivo flow model using porcine iliac arteries, obtained from a local abattoir. Twenty arteries (of 10 pigs) were equally allocated to two groups: a mock-treated control group and an endovascular intervention group. Arteries of both groups were perfused with porcine blood for 9 min, including 3 min of balloon angioplasty in the intervention group. Vessel injury was assessed by calculating the presence of endothelial cell denudation, vasomotor function, and histopathological analysis. MR imaging displayed balloon positioning and inflation. Endothelial cell staining showed 76% of denudation after ballooning compared to 6% in the control group (p < 0.001). This was confirmed by histopathological analysis, showing a significantly reduced endothelial nuclei count after ballooning compared to the controls (median: 22 vs. 37 nuclei/mm, p = 0.022). In the intervention group, vasoconstriction and endothelium-dependent relaxation were significantly reduced (p < 0.05).We present an ex vivo flow model to test the effects of endovascular therapy on the vessel's wall morphology, endothelial denudation, and endothelial-dependent vasomotor function under physiological conditions. Additionally, it allows the future testing of human arterial tissue.

Distribution of decidual mast cells in fetal growth restriction and stillbirth at (near) term

INTRODUCTION

Placental pathology and pregnancy complications are associated with unfavorable regulation of the maternal immune system. Although much research has been performed towards the role of immune cells like macrophages and T cells in this context, little is known about the presence and function of mast cells (MC). MC can be sub classified in tryptase-positive (MC_T) and tryptase- and chymase-positive (MC_TC). This study investigates the presence of MC in the decidua of pregnancies complicated by fetal growth restriction (FGR) and stillbirth (SB).

METHODS

Placental tissue from FGR (n = 250), SB (n = 64) and healthy pregnancies (n = 42) was included. Histopathological lesions were classified according to the Amsterdam Placental Workshop Group criteria. Tissue sections were stained for tryptase and chymase. Decidual MC were counted manually, and the results were expressed as number of cells/mm² decidual tissue.

RESULTS

A significant lower median number of MC_TC was found in the decidua of FGR (0.40 per mm²; p < 0.001) and SB (0.51 per mm²; p < 0.05) compared to healthy controls (1.04 per mm²). No difference in MC_T number (1.19 per mm², 1.88 per mm² and 1.37 per mm² respectively) was seen between the groups. There was no difference in number of MC_T and MC_TC between placental pathological lesions.

DISCUSSION

Our findings suggest a shift in decidual MC balance towards MC_T in pregnancy complications. No difference in numbers of MC subtypes was found to be related to histopathologic lesions.

[18F]FDG and [18F]NaF as PET markers of systemic atherosclerosis progression: A longitudinal descriptive imaging study in patients with type 2 diabetes mellitus

BACKGROUND

While [18F]-fluordeoxyglucose ([18F]FDG) uptake is associated with arterial inflammation, [18F]-sodium fluoride ([18F]NaF) is a marker for arterial micro-calcification. We aimed to investigate the prospective correlation between both PET markers over time and whether they are prospectively ([18F]FDG) and retrospectively ([18F]NaF) related to progression of systemic arterial disease in a longitudinal study in patients with type 2 diabetes mellitus (T2DM).

METHODS

Baseline [18F]FDG PET/Low Dose (LD) Computed Tomography (CT) scans of ten patients with early T2DM without cardiovascular history (70% men, median age 63 years) were compared with five-year follow-up [18F]NaF/LDCT scans. Systemic activity was expressed as mean target-to-background ratio (meanTBR) by dividing the maximal standardized uptake value (SUVmax) of ten arteries by SUVmean of the caval vein. CT-assessed macro-calcifications were scored visually and expressed as calcified plaque (CP) score. Arterial stiffness was assessed with carotid-femoral pulse wave velocity (PWV). Five-year changes were expressed absolutely with delta (Δ) and relatively with %change.

RESULTS

Baseline meanTBR[18F]FDG was strongly correlated with five-year follow-up meanTBR[18F]NaF (r = 0.709, P = .022). meanTBR[18F]NaF correlated positively with ΔCPscore, CPscore at baseline, and follow-up (r = 0.845, P = .002 and r = 0.855, P = .002, respectively), but not with %change in CPscore and PWV.

CONCLUSION

This proof-of-concept study demonstrated that systemic arterial inflammation is an important pathogenetic factor in systemic arterial micro-calcification development.

Prevention of Triglyceridemia by (Non-)Anticoagulant Heparin(oids) Does Not Preclude Transplant Vasculopathy and Glomerulosclerosis

Background: In renal transplantation, chronic transplant dysfunction (CTD) is associated with increased PCSK9 and dyslipidemia. PCSK9 is an enzyme that increases plasma cholesterol levels by downregulating LDLR expression. We recently showed increased PCSK9-syndecan-1 interaction in conditions of proteinuria and renal function loss. Treatment with heparin(oids) might be a therapeutic option to improve dyslipidemia and CTD. We investigated the effects of (non-)anticoagulant heparin(oids) on serum lipids, syndecan-1 and PCSK9 levels, and CTD development. Methods: Kidney allotransplantation was performed from female Dark Agouti to male Wistar Furth recipients. Transplanted rats received daily subcutaneous injections of saline, unfractionated heparin, and RO-heparin or NAc-heparin (2 mg heparin(oid)/kg BW) until sacrifice after 9 weeks of treatment. Results: Saline-treated recipients developed hypertension, proteinuria, and loss of creatinine clearance (all p < 0.05 compared to baseline), along with glomerulosclerosis and arterial neo-intima formation. Saline-treated recipients showed significant increase in plasma triglycerides (p < 0.05), borderline increase in non-HDLc/HDLc (p = 0.051), and ∼10-fold increase in serum syndecan-1 (p < 0.05), without significant increase in serum PCSK9 at 8 weeks compared to baseline. Heparin and non-anticoagulant RO-heparin administration in transplanted rats completely prevented an increase in triglycerides compared to saline-treated recipients at 8 weeks (both p < 0.05). Heparin(oids) treatment did not influence serum total cholesterol (TC), plasma syndecan-1 and PCSK9 levels, creatinine clearance, proteinuria, glomerulosclerosis, and arterial neo-intima formation, 8 weeks after transplantation. Combining all groups, increased syndecan-1 shedding was associated with TC (r = 0.5; p = 0.03) and glomerulosclerosis (r = 0.53; p = 0.021), whereas the non-HDLc/HDLc ratio was associated with the neo-intimal score in the transplanted kidneys (r = 0.65; p < 0.001). Conclusion: Prevention of triglyceridemia by (non-)anticoagulant heparin(oids) neither influenced PCSK9/syndecan-1 nor precluded CTD, which however did associate with the shedding of lipoprotein clearance receptor syndecan-1 and the unfavorable cholesterol profile.

Glycaemia dynamics in gestational diabetes mellitus

Pregnant women may develop gestational diabetes mellitus (GDM), a disease of pregnancy characterised by maternal and fetal hyperglycaemia with hazardous consequences to the mother, the fetus, and the newborn. Maternal hyperglycaemia in GDM results in fetoplacental endothelial dysfunction. GDM-harmful effects result from chronic and short periods of hyperglycaemia. Thus, it is determinant to keep glycaemia within physiological ranges avoiding short but repetitive periods of hyper or hypoglycaemia. The variation of glycaemia over time is defined as 'glycaemia dynamics'. The latter concept regards with a variety of mechanisms and environmental conditions leading to blood glucose handling. In this review we summarized the different metrics for glycaemia dynamics derived from quantitative, plane distribution, amplitude, score values, variability estimation, and time series analysis. The potential application of the derived metrics from self-monitoring of blood glucose (SMBG) and continuous glucose monitoring (CGM) in the potential alterations of pregnancy outcome in GDM are discussed.

SARS-CoV-2 infects the human kidney and drives fibrosis in kidney organoids

Kidney failure is frequently observed during and after COVID-19, but it remains elusive whether this is a direct effect of the virus. Here, we report that SARS-CoV-2 directly infects kidney cells and is associated with increased tubule-interstitial kidney fibrosis in patient autopsy samples. To study direct effects of the virus on the kidney independent of systemic effects of COVID-19, we infected human-induced pluripotent stem-cell-derived kidney organoids with SARS-CoV-2. Single-cell RNA sequencing indicated injury and dedifferentiation of infected cells with activation of profibrotic signaling pathways. Importantly, SARS-CoV-2 infection also led to increased collagen 1 protein expression in organoids. A SARS-CoV-2 protease inhibitor was able to ameliorate the infection of kidney cells by SARS-CoV-2. Our results suggest that SARS-CoV-2 can directly infect kidney cells and induce cell injury with subsequent fibrosis. These data could explain both acute kidney injury in COVID-19 patients and the development of chronic kidney disease in long COVID.

•

COVID-19 patients present tubulo-interstitial kidney fibrosis compared with controls

•

SARS-CoV-2 infection stimulates profibrotic signaling in human kidney organoids

•

SARS-CoV-2 infection can be inhibited by a protease blocker in human kidney organoids

Perivascular adipose tissue-derived nitric oxide compensates endothelial dysfunction in aged pre-atherosclerotic apolipoprotein E-deficient rats

BACKGROUND AND AIMS

Atherosclerosis is a major contributor to global mortality and is accompanied by vascular inflammation and endothelial dysfunction. Perivascular adipose tissue (PVAT) is an established regulator of vascular function with emerging implications in atherosclerosis. We investigated the modulation of aortic relaxation by PVAT in aged rats with apolipoprotein E deficiency (ApoE^-/-) fed a high-fat diet as a model of early atherosclerosis.

METHODS AND RESULTS

ApoE^-/- rats (N = 7) and wild-type Sprague-Dawley controls (ApoE^+/+, N = 8) received high-fat diet for 51 weeks. Hyperlipidemia was confirmed in ApoE^-/- rats by elevated plasma cholesterol (p < 0.001) and triglyceride (p = 0.025) levels. Early atherosclerosis was supported by increased intima/media thickness ratio (p < 0.01) and ED1-positive macrophage influx in ApoE^-/- aortic intima (p < 0.001). Inflammation in ApoE^-/- PVAT was characteristic by an increased [18F]FDG uptake (p < 0.01), ED1-positive macrophage influx (p = 0.0003), mRNA expression levels of CD68 (p < 0.001) and IL-1β (p < 0.01), and upregulated iNOS protein (p = 0.011). The mRNAs of MCP-1, IL-6 and adiponectin remained unchanged in PVAT. Aortic PVAT volume measured with micro-PET/CT was increased in ApoE^-/- rats (p < 0.01). Maximal endothelium-dependent relaxation (EDR) to acetylcholine in ApoE^-/- aortic rings without PVAT was severely impaired (p = 0.012) compared with controls, while ApoE^-/- aortic rings with PVAT showed higher EDR than controls. All EDR responses were blocked by L-NMMA and the expression of eNOS mRNA was increased in ApoE^-/- PVAT (p = 0.035).

CONCLUSION

Using a rat ApoE^-/- model of early atherosclerosis, we capture a novel mechanism by which inflammatory PVAT compensates severe endothelial dysfunction by contributing NO upon cholinergic stimulation.

N-Acetylcysteine and Hydrogen Sulfide in Coronavirus Disease 2019

Significance: Hydrogen sulfide (H₂S) is one of the three main gasotransmitters that are endogenously produced in humans and are protective against oxidative stress. Recent findings from studies focusing on coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), shifted our attention to a potentially modulatory role of H₂S in this viral respiratory disease. Recent Advances: H₂S levels at hospital admission may be of importance since this gasotransmitter has been shown to be protective against lung damage through its antiviral, antioxidant, and anti-inflammatory actions. Furthermore, many COVID-19 cases have been described demonstrating remarkable clinical improvement upon administration of high doses of N-acetylcysteine (NAC). NAC is a renowned pharmacological antioxidant substance acting as a source of cysteine, thereby promoting endogenous glutathione (GSH) biosynthesis as well as generation of sulfane sulfur species when desulfurated to H₂S. Critical Issues: Combining H₂S physiology and currently available knowledge of COVID-19, H₂S is hypothesized to target three main vulnerabilities of SARS-CoV-2: (i) cell entry through interfering with functional host receptors, (ii) viral replication through acting on RNA-dependent RNA polymerase (RdRp), and (iii) the escalation of inflammation to a potentially lethal hyperinflammatory cytokine storm (toll-like receptor 4 [TLR4] pathway and NLR family pyrin domain containing 3 [NLRP3] inflammasome). Future Directions: Dissecting the breakdown of NAC reveals the possibility of increasing endogenous H₂S levels, which may provide a convenient rationale for the application of H₂S-targeted therapeutics. Further randomized-controlled trials are warranted to investigate its definitive role.

Plasma Nitrate Levels Are Related to Metabolic Syndrome and Are Not Altered by Treatment with DPP-4 Inhibitor Linagliptin: A Randomised, Placebo-Controlled Trial in Patients with Early Type 2 Diabetes Mellitus

The depletion of nitrate and nitrite, stable nitric oxide (NO) end-products, promotes adipose tissue dysfunction and insulin resistance (IR). Dipeptidyl peptidase-4 (DPP-4) inhibitors have the potentially beneficial side effect of increasing NO availability. In this study, nitrate and nitrite levels and the effects of DPP-4 inhibitor linagliptin were investigated in relation to metabolic syndrome (MetS) markers. Treatment-naive patients with early type 2 diabetes mellitus (T2DM) (n = 40, median age 63 IQR (55–67) years, 63% male, mean HbA1c 45 ± 4.4 mmol/mol) were randomized (1:1) to linagliptin (5 mg/day) or placebo. MetS-related markers (body mass index (BMI), triglycerides, HOMA-IR, gamma-glutamyltransferase (GGT), C-reactive protein (CRP), and adiponectin), plasma levels of nitrate, nitrite, total free thiols (TFT) and vegetable intake were estimated at baseline and after 4 and 26 weeks of treatment. Plasma nitrate, but not nitrite, correlated positively with vegetable intake (r = 0.38, p = 0.018) and was inversely associated with HOMA-IR (r = −0.44, p = 0.006), BMI (r = −0.35, p = 0.028), GGT (r = −0.37, p = 0.019) and CRP (r = −0.34, p = 0.034). The relationship between nitrate and HOMA-IR remained significant after adjusting for BMI, CRP, vegetable intake and GGT. With stable vegetable intake, nitrate and nitrite, TFT, adipokines and CRP did not change after 26 weeks of linagliptin treatment. While plasma nitrate is inversely associated with MetS, linagliptin treatment does not significantly influence nitrate and nitrite concentrations, oxidative stress, adipose tissue function and systemic inflammation.

Oxidative stress biomarkers in fetal growth restriction with and without preeclampsia

INTRODUCTION

Oxidative stress as observed in fetal growth restriction (FGR) and preeclampsia (PE) can be identified by decreased levels of systemic free thiols (FT) and increased levels of plasma ischemia-modified albumin (IMA), which may serve as biomarkers in maternal blood for pregnancy complications. We evaluate the performance of oxidative stress-associated potential biomarkers for FGR and PE, and their relationship with clinical characteristics.

METHODS

A prospective clinical pilot study was performed in healthy controls and women with pregnancies complicated by severe FGR with or without PE. Blood samples were taken directly after inclusion and analyzed for FT; IMA; soluble FMS-like tyrosine kinase-1 (sFlt-1); placenta growth factor (PlGF); and biomarkers like leptin and soluble receptors for advanced glycation end products (sRAGE). Placentas were examined microscopically. Descriptive statistics and receiver operating characteristics statistics were performed.

RESULTS

Mothers with both severe FGR and PE had significantly reduced FT levels (p < 0.001) and PlGF levels (p < 0.001), and increased levels of plasma IMA (p < 0.05), sFlt (p < 0.001), leptin (p < 0.05) and sRAGE (p < 0.01) compared to women with FGR only. Systemic FT levels were significantly inversely associated with blood pressure (p < 0.01) and plasma IMA (p < 0.001), leptin (p = 0.01) and sRAGE (p < 0.001). Systemic FT and leptin showed significant discriminative ability to differentiate mothers with both FGR and PE from mothers with uncomplicated pregnancies or pregnancies complicated by FGR only.

DISCUSSION

There is a significant discriminative capacity of FT, IMA, leptin and sRAGE that harbor potential as biomarkers of pregnancies complicated by combined FGR and PE.

Magnetic resonance imaging assessment of renal flow distribution patterns during ex vivo normothermic machine perfusion in porcine and human kidneys

Acceptance criteria of deceased donor organs have gradually been extended toward suboptimal quality, posing an urgent need for more objective pre‐transplant organ assessment. Ex vivo normothermic machine perfusion (NMP) combined with magnetic resonance imaging (MRI) could assist clinicians in deciding whether a donor kidney is suitable for transplantation. Aim of this study was to characterize the regional distribution of perfusate flow during NMP, to better understand how ex vivo kidney assessment protocols should eventually be designed. Nine porcine and 4 human discarded kidneys underwent 3 h of NMP in an MRI‐compatible perfusion setup. Arterial spin labeling scans were performed every 15 min, resulting in perfusion‐weighted images that visualize intrarenal flow distribution. At the start of NMP, all kidneys were mainly centrally perfused and it took time for the outer cortex to reach its physiological dominant perfusion state. Calculated corticomedullary ratios based on the perfusion maps reached a physiological range comparable to in vivo observations, but only after 1 to 2 h after the start of NMP. Before that, the functionally important renal cortex appeared severely underperfused. Our findings suggest that early functional NMP quality assessment markers may not reflect actual physiology and should therefore be interpreted with caution.

Characterization of apolipoprotein E-deficient rats as novel model for atherosclerosis imaging

Funding Acknowledgements

Type of funding sources: None.

Background

The apolipoprotein E-deficient (apoE-/-) mouse is a well-established atherosclerotic model with impaired lipoprotein clearance and development of vessel plaques. However, the small size of the mouse limits its use as an animal model in longitudinal positron emission tomography (PET) imaging studies of atherosclerosis. Recently, apoE-/- rats have become available. This study addresses the suitability of the apoE-/- rat as model for atherosclerotic PET imaging.

Methods

Ten male apoE-/- rats and ten male control rats (apoE+/+) (age 10+/-1 weeks), each fed with a Western diet, were injected at baseline week 4, 12, 26 and 51, with 60 MBq of [18F]2-fluoro-2-deoxy-D-glucose. Plasma cholesterol, body weight and fat were measured. 3h after injection, a computed tomography (CT) and a 20-min PET scan were made. After the final scan, aortic tissue was collected for histological staining.

Results

Cholesterol levels started to increase after 4 weeks in the apoE-/- rats, whereas in the apoE+/+ rats levels stayed stable. Body weight and body fat increased more rapidly in the apoE-/- rats but were similar in both strains at the end of the study. SUVmean and max in the aortic arch and abdominal aorta were significantly higher (p &lt; 0.001) in apoE-/- versus apoE+/+ rats at weeks 12, 26 and 51. Oil red O staining showed lesions in 20.0 % of the surface of the aortic arch in the apoE-/- rats. Hardly no fatty streaks were detected in the apoE+/+ rats (2.29%). More histology data is being analyzed.

Conclusion

Plasma cholesterol levels were elevated in apoE-/- rats. PET imaging demonstrated differences in [18F]-FDG uptake in the aortic arch and abdominal aorta after 12, 26 and 51 weeks. Combined, these data demonstrate that apoE-/- rats represent a useful preclinical model for the non-invasive assessment of atherosclerosis in longitudinal studies.

VEGF-Targeted Multispectral Optoacoustic Tomography and Fluorescence Molecular Imaging in Human Carotid Atherosclerotic Plaques

Vulnerable atherosclerotic carotid plaques are prone to rupture, resulting in ischemic strokes. In contrast to radiological imaging techniques, molecular imaging techniques have the potential to assess plaque vulnerability by visualizing diseases-specific biomarkers. A risk factor for rupture is intra-plaque neovascularization, which is characterized by overexpression of vascular endothelial growth factor-A (VEGF-A). Here, we study if administration of bevacizumab-800CW, a near-infrared tracer targeting VEGF-A, is safe and if molecular assessment of atherosclerotic carotid plaques in vivo is possible using multispectral optoacoustic tomography (MSOT). Healthy volunteers and patients with symptomatic carotid artery stenosis scheduled for carotid artery endarterectomy were imaged with MSOT. Secondly, patients were imaged two days after intravenous administration of 4.5 bevacizumab-800CW. Ex vivo fluorescence molecular imaging of the surgically removed plaque specimen was performed and correlated with histopathology. In this first-in-human MSOT and fluorescence molecular imaging study, we show that administration of 4.5 mg bevacizumab-800CW appeared to be safe in five patients and accumulated in the carotid atherosclerotic plaque. Although we could visualize the carotid bifurcation area in all subjects using MSOT, bevacizumab-800CW-resolved signal could not be detected with MSOT in the patients. Future studies should evaluate tracer safety, higher doses of bevacizumab-800CW or develop dedicated contrast agents for carotid atherosclerotic plaque assessment using MSOT.

Calciprotein Particles: Balancing Mineral Homeostasis and Vascular Pathology

[Figure: see text].

Cardiac Protection by Oral Sodium Thiosulfate in a Rat Model of L-NNA-Induced Heart Disease

Hypertension contributes to cardiac damage and remodeling. Despite the availability of renin-angiotensin system inhibitors and other antihypertensive therapies, some patients still develop heart failure. Novel therapeutic approaches are required that are effective and without major adverse effects. Sodium Thiosulfate (STS), a reversible oxidation product of hydrogen sulfide (H₂S), is a promising pharmacological entity with vasodilator and anti-oxidant potential that is clinically approved for the treatment of calciphylaxis and cyanide poisoning. We hypothesized that Sodium Thiosulfate improves cardiac disease in an experimental hypertension model and sought to investigate its cardioprotective effects by direct comparison to the ACE-inhibitor lisinopril, alone and in combination, using a rat model of chronic nitric oxide (NO) deficiency. Systemic nitric oxide production was inhibited in Sprague Dawley rats by administering N-ω-nitro-l-arginine (L-NNA) with the food for three weeks, leading to progressive hypertension, cardiac dysfunction and remodeling. We observed that STS, orally administered via the drinking water, ameliorated L-NNA-induced heart disease. Treatment with STS for two weeks ameliorated hypertension and improved systolic function, left ventricular hypertrophy, cardiac fibrosis and oxidative stress, without causing metabolic acidosis as is sometimes observed following parenteral administration of this drug. STS and lisinopril had similar protective effects that were not additive when combined. Our findings indicate that oral intervention with a H₂S donor such as STS has cardioprotective properties without noticeable side effects.

Feasibility of ex vivo fluorescence imaging of angiogenesis in (non-) culprit human carotid atherosclerotic plaques using bevacizumab-800CW

Vascular endothelial growth factor-A (VEGF-A) is assumed to play a crucial role in the development and rupture of vulnerable plaques in the atherosclerotic process. We used a VEGF-A targeted fluorescent antibody (bevacizumab-IRDye800CW [bevacizumab-800CW]) to image and visualize the distribution of VEGF-A in (non-)culprit carotid plaques ex vivo. Freshly endarterectomized human plaques (n = 15) were incubated in bevacizumab-800CW ex vivo. Subsequent NIRF imaging showed a more intense fluorescent signal in the culprit plaques (n = 11) than in the non-culprit plaques (n = 3). A plaque received from an asymptomatic patient showed pathologic features similar to the culprit plaques. Cross-correlation with VEGF-A immunohistochemistry showed co-localization of VEGF-A over-expression in 91% of the fluorescent culprit plaques, while no VEGF-A expression was found in the non-culprit plaques (p < 0.0001). VEGF-A expression was co-localized with CD34, a marker for angiogenesis (p < 0.001). Ex vivo near-infrared fluorescence (NIRF) imaging by incubation with bevacizumab-800CW shows promise for visualizing VEGF-A overexpression in culprit atherosclerotic plaques in vivo.

Serum calcification propensity is associated with HbA1c in type 2 diabetes mellitus

INTRODUCTION

Serum calcification propensity is emerging as an independent predictor for cardiovascular outcomes in high-risk populations. Calcification propensity can be monitored by the maturation time of calciprotein particles in serum (T₅₀ test). A low T₅₀ value is an independent determinant of cardiovascular morbidity and mortality in various populations. Aim was to investigate the T₅₀ and its relationship to type 2 diabetes mellitus.

RESEARCH DESIGN AND METHODS

Using nephelometry, serum T₅₀ was cross-sectionally measured in 932 stable patients with type 2 diabetes mellitus (55% male) with a median age of 66 (62-75) years, diabetes duration of 6.5 (3.0-10.2) years and hemoglobin A1c (HbA1c) of 49 (44-54) mmol/mol.

RESULTS

Serum T₅₀ was normally distributed with a mean value of 261±66 min. In linear regression, serum T₅₀ was lower in women and current smokers. A lower T₅₀ value was found in patients with a higher HbA1c or higher systolic blood pressure, insulin users and patients with a longer history of diabetes. The association with HbA1c was independent of other determinants in multivariable analysis. There was no association between T₅₀ and previous macrovascular events or the presence of microvascular disease.

CONCLUSIONS

Serum calcification propensity is independently associated with glycemic control, suggesting that a lower HbA1c may be associated with better cardiovascular outcomes. Retrospective analysis could not establish an association between a history of macrovascular events and T₅₀, and prospective studies will have to be performed to address this hypothesis.

TRIAL REGISTRATION NUMBER

NCT01570140.

Glomerular Endothelial Cells as Instigators of Glomerular Sclerotic Diseases

Glomerular endothelial cell (GEnC) dysfunction is important in the pathogenesis of glomerular sclerotic diseases, including Focal Segmental Glomerulosclerosis (FSGS) and overt diabetic nephropathy (DN). GEnCs form the first cellular barrier in direct contact with cells and factors circulating in the blood. Disturbances in these circulating factors can induce GEnC dysfunction. GEnC dysfunction occurs in early stages of FSGS and DN, and is characterized by a compromised endothelial glycocalyx, an inflammatory phenotype, mitochondrial damage and oxidative stress, aberrant cell signaling, and endothelial-to-mesenchymal transition (EndMT). GEnCs are in an interdependent relationship with podocytes and mesangial cells, which involves bidirectional cross-talk via intercellular signaling. Given that GEnC behavior directly influences podocyte function, it is conceivable that GEnC dysfunction may culminate in podocyte damage, proteinuria, subsequent mesangial activation, and ultimately glomerulosclerosis. Indeed, GEnC dysfunction is sufficient to cause podocyte injury, proteinuria and activation of mesangial cells. Aberrant gene expression patterns largely contribute to GEnC dysfunction and epigenetic changes seem to be involved in causing aberrant transcription. This review summarizes literature that uncovers the importance of cross-talk between GEnCs and podocytes, and GEnCs and mesangial cells in the context of the development of FSGS and DN, and the potential use of GEnCs as efficacious cellular target to pharmacologically halt development and progression of DN and FSGS.

Effects of Sodium-Glucose Co-transporter 2 Inhibition with Empaglifozin on Renal Structure and Function in Non-diabetic Rats with Left Ventricular Dysfunction After Myocardial Infarction

Background

The use of sodium–glucose co-transporter 2 inhibitors (SGLT2i) is currently expanding to cardiovascular risk reduction in non-diabetic subjects, but renal (side-)effects are less well studied in this setting.

Methods

Male non-diabetic Sprague Dawley rats underwent permanent coronary artery ligation to induce MI, or sham surgery. Rats received chow containing empagliflozin (EMPA) (30 mg/kg/day) or control chow. Renal function and electrolyte balance were measured in metabolic cages. Histological and molecular markers of kidney injury, parameters of phosphate homeostasis and bone resorption were also assessed.

Results

EMPA resulted in a twofold increase in diuresis, without evidence for plasma volume contraction or impediments in renal function in both sham and MI animals. EMPA increased plasma magnesium levels, while the levels of glucose and other major electrolytes were comparable among the groups. Urinary protein excretion was similar in all treatment groups and no histomorphological alterations were identified in the kidney. Accordingly, molecular markers for cellular injury, fibrosis, inflammation and oxidative stress in renal tissue were comparable between groups. EMPA resulted in a slight increase in circulating phosphate and PTH levels without activating FGF23–Klotho axis in the kidney and bone mineral resorption, measured with CTX-1, was not increased.

Conclusions

EMPA exerts profound diuretic effects without compromising renal structure and function or causing significant electrolyte imbalance in a non-diabetic setting. The slight increase in circulating phosphate and PTH after EMPA treatment was not associated with evidence for increased bone mineral resorption suggesting that EMPA does not affect bone health.

Electronic supplementary material

The online version of this article (10.1007/s10557-020-06954-6) contains supplementary material, which is available to authorized users.

[18F]FDG Uptake in Adipose Tissue Is Not Related to Inflammation in Type 2 Diabetes Mellitus

Purpose

2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) uptake is a marker of metabolic activity and is therefore used to measure the inflammatory state of several tissues. This radionuclide marker is transported through the cell membrane via glucose transport proteins (GLUTs). The aim of this study is to investigate whether insulin resistance (IR) or inflammation plays a role in [¹⁸F]FDG uptake in adipose tissue (AT).

Procedures

This study consisted of an in vivo clinical part and an ex vivo mechanistic part. In the clinical part, [¹⁸F]FDG uptake in abdominal visceral AT (VAT) and subcutaneous AT (SAT) was determined using PET/CT imaging in 44 patients with early type 2 diabetes mellitus (T2DM) (age 63 [54–66] years, HbA1c [6.3 ± 0.4 %], HOMA-IR 5.1[3.1–8.5]). Plasma levels were measured with ELISA. In the mechanistic part, AT biopsies obtained from 8 patients were ex vivo incubated with [¹⁸F]FDG followed by autoradiography. Next, a qRT-PCR analysis was performed to determine GLUT and cytokine mRNA expression levels. Immunohistochemistry was performed to determine CD68⁺ macrophage infiltration and GLUT4 protein expression in AT.

Results

In vivo VAT [¹⁸F]FDG uptake in patients with T2DM was inversely correlated with HOMA-IR (r = − 0.32, p = 0.034), and positively related to adiponectin plasma levels (r = 0.43, p = 0.003). Ex vivo [¹⁸F]FDG uptake in VAT was not related to CD68⁺ macrophage infiltration, and IL-1ß and IL-6 mRNA expression levels. Ex vivo VAT [¹⁸F]FDG uptake was positively related to GLUT4 (r = 0.83, p = 0.042), inversely to GLUT3 (r = − 0.83, p = 0.042) and not related to GLUT1 mRNA expression levels.

Conclusions

In vivo [¹⁸F]FDG uptake in VAT from patients with T2DM is positively correlated with adiponectin levels and inversely with IR. Ex vivo [¹⁸F]FDG uptake in AT is associated with GLUT4 expression but not with pro-inflammatory markers. The effect of IR should be taken into account when interpreting data of [¹⁸F]FDG uptake as a marker for AT inflammation.

Electronic supplementary material

The online version of this article (10.1007/s11307-020-01538-0) contains supplementary material, which is available to authorized users.

Angiotensin-converting enzyme 2 (ACE2), SARS-CoV-2 and the pathophysiology of coronavirus disease 2019 (COVID-19)

Angiotensin-converting enzyme 2 (ACE2) has been established as the functional host receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the current devastating worldwide pandemic of coronavirus disease 2019 (COVID-19). ACE2 is abundantly expressed in a variety of cells residing in many different human organs. In human physiology, ACE2 is a pivotal counter-regulatory enzyme to ACE by the breakdown of angiotensin II, the central player in the renin-angiotensin-aldosterone system (RAAS) and the main substrate of ACE2. Many factors have been associated with both altered ACE2 expression and COVID-19 severity and progression, including age, sex, ethnicity, medication, and several co-morbidities, such as cardiovascular disease and metabolic syndrome. Although ACE2 is widely distributed in various human tissues and many of its determinants have been well recognised, ACE2-expressing organs do not equally participate in COVID-19 pathophysiology, implying that other mechanisms are involved in orchestrating cellular infection resulting in tissue damage. Reports of pathologic findings in tissue specimens of COVID-19 patients are rapidly emerging and confirm the established role of ACE2 expression and activity in disease pathogenesis. Identifying pathologic changes caused by SARS-CoV-2 infection is crucially important as it has major implications for understanding COVID-19 pathophysiology and the development of evidence-based treatment strategies. Currently, many interventional strategies are being explored in ongoing clinical trials, encompassing many drug classes and strategies, including antiviral drugs, biological response modifiers, and RAAS inhibitors. Ultimately, prevention is key to combat COVID-19 and appropriate measures are being taken accordingly, including development of effective vaccines. In this review, we describe the role of ACE2 in COVID-19 pathophysiology, including factors influencing ACE2 expression and activity in relation to COVID-19 severity. In addition, we discuss the relevant pathological changes resulting from SARS-CoV-2 infection. Finally, we highlight a selection of potential treatment modalities for COVID-19. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Serum Calcification Propensity and the Risk of Cardiovascular and All-Cause Mortality in the General Population: The PREVEND Study

OBJECTIVE

Vascular calcification contributes to the cause of cardiovascular disease. The calciprotein particle maturation time (T₅₀) in serum, a measure of calcification propensity, has been linked with adverse outcomes in patients with chronic kidney disease, but its role in the general population is unclear. We investigated whether serum T₅₀ is associated with cardiovascular mortality in a large general population-based cohort. Approach and Results: The relationship between serum T₅₀ and cardiovascular mortality was studied in 6231 participants of the PREVEND (Prevention of Renal and Vascular End-Stage Disease) cohort. All-cause mortality was the secondary outcome. Mean (±SD) age was 53±12 years, 50% were male, and mean serum T₅₀ was 329±58 minutes. A shorter serum T₅₀ is indicative of a higher calcification propensity. Serum T₅₀ was inversely associated with circulating phosphate, age, estimated glomerular filtration rate, and alcohol consumption, whereas plasma magnesium was positively associated with serum T₅₀ (P<0.001, total multivariable model R²=0.281). During median (interquartile range) follow-up for 8.3 (7.8-8.9) years, 364 patients died (5.8%), of whom 95 (26.1%) died from a cardiovascular cause. In multivariable Cox proportional hazard models, each 60 minutes decrease in serum T₅₀ was independently associated with a higher risk of cardiovascular mortality (fully adjusted hazard ratio [95% CI], 1.22 [1.04-1.36], P=0.021). This association was modified by diabetes mellitus; stratified analysis indicated a more pronounced association in individuals with diabetes mellitus.

CONCLUSIONS

Serum T₅₀ is independently associated with an increased risk of cardiovascular mortality in the general population and thus may be an early and potentially modifiable risk marker for cardiovascular mortality.

The Effect of a Fast-Releasing Hydrogen Sulfide Donor on Vascularization of Subcutaneous Scaffolds in Immunocompetent and Immunocompromised Mice

Islet transplantation into subcutaneous polymer scaffolds has shown to successfully induce normoglycemia in type 1 diabetes models. Vascularization of these scaffolds is imperative for optimal control of glucose levels. We studied the effect of the vascular stimulator hydrogen sulfide (H₂S) on the degree of vascularization of a scaffold and the role of the immune system in this process. Scaffolds were subcutaneously implanted in immunocompetent C57BL/6 and immunocompromised nude mice. Mice received twice-daily intraperitoneal injections of the fast-releasing H₂S donor sodium hydrosulfide (NaHS, 25 or 50 μmol/kg) or saline for 28 days. After 63 days the vascular network was analyzed by histology and gene expression. Here we showed that the vascularization of a subcutaneous scaffold in nude mice was significantly impaired by H₂S treatment. Both the CD31 gene and protein expression were reduced in these scaffolds compared to the saline-treated controls. In C57BL/6 mice, the opposite was found, the vascularization of the scaffold was significantly increased by H₂S. The mRNA expression of the angiogenesis marker CD105 was significantly increased compared to the controls as well as the number of CD31 positive blood vessels. In conclusion, the immune system plays an important role in the H₂S mediated effect on vascularization of subcutaneous scaffolds.

Activation of Retinal Angiogenesis in Hyperglycemic pdx1 -/- Zebrafish Mutants

Progression from the initial vascular response upon hyperglycemia to a proliferative stage with neovacularizations is the hallmark of proliferative diabetic retinopathy. Here, we report on the novel diabetic pdx1 ^-/- zebrafish mutant as a model for diabetic retinopathy that lacks the transcription factor pdx1 through CRISPR-Cas9-mediated gene knockout leading to disturbed pancreatic development and hyperglycemia. Larval pdx1 ^-/- mutants prominently show vasodilation of blood vessels through increased vascular thickness in the hyaloid network as direct developmental precursor of the adult retinal vasculature in zebrafish. In adult pdx1 ^-/- mutants, impaired glucose homeostasis induces increased hyperbranching and hypersprouting with new vessel formation in the retina and aggravation of the vascular alterations from the larval to the adult stage. Both vascular aspects respond to antiangiogenic and antihyperglycemic pharmacological interventions in the larval stage and are accompanied by alterations in the nitric oxide metabolism. Thus, the pdx1 ^-/- mutant represents a novel model to study mechanisms of hyperglycemia-induced retinopathy wherein extensive proangiogenic alterations in blood vessel morphology and metabolic alterations underlie the vascular phenotype.

Favourable serum calcification propensity with intraperitoneal as compared with subcutaneous insulin administration in type 1 diabetes

BACKGROUND

Serum calcification propensity can be monitored using the maturation time of calciprotein particles in serum (T₅₀ test). A shorter T₅₀ indicates greater propensity to calcify; this is an independent determinant of cardiovascular disease. As the intraperitoneal (IP) route of insulin administration mimics the physiology more than the subcutaneous (SC) route in persons with type 1 diabetes (T1DM), we hypothesized that IP insulin influences determinants of calcium propensity and therefore result in a longer T₅₀ than SC insulin administration.

METHODS

Prospective, observational case-control study. Measurements were performed at baseline and at 26 weeks in age and gender matched persons with T1DM.

RESULTS

A total of 181 persons, 39 (21.5%) of which used IP and 142 (78.5%) SC insulin were analysed. Baseline T₅₀ was 356 (45) minutes. The geometric mean T₅₀ significantly differed between both treatment groups: 367 [95% confidence interval (CI) 357, 376] for the IP group and 352 (95% CI 347, 357) for the SC group with a difference of -15 (95% CI -25, -4) minutes, in favour of IP treatment. In multivariable analyses, the IP route of insulin administration had a positive relation on T₅₀ concentrations while higher age, triglycerides and phosphate concentrations had an inverse relation.

CONCLUSION

Among persons with T1DM, IP insulin administration results in a more favourable calcification propensity time then SC insulin. It has yet to be shown if this observation translates into improved cardiovascular outcomes.

Serum calcification propensity in type 1 diabetes associates with mineral stress

AIMS

Increased vascular calcification could be an underlying mechanism of cardiovascular complications in type 1 diabetes mellitus (T1DM). Calcificationpropensitycan be monitored by the maturation time of calciprotein particles in serum (T₅₀ test). A high calcification propensity (i.e. low T₅₀-value) is an independent determinant of mortality in various populations. Aim was to investigate T₅₀levels with indices of calcium metabolism and disease status in T1DM patients.

METHODS

As part of a prospective cohort study, T1DM patients were examined annually. At baseline T₅₀ was determined in 216 (77%) patients (57% male) with a mean age of 45 (12) years, diabetes duration 22 [15.8, 30.4] years and HbA1c of 60 (12) mmol/mol (7.6 (1.0) %). Baseline data were collected in 2002 and follow-up data were collected in 2018.

RESULTS

The T₅₀ time was normally distributed with a mean of 339 (60) minutes. Patients in the highest tertile of T₅₀ (range 369-466) were older, had lower phosphate and PTH and higher magnesium and vitamin D concentrations as compared to the middle (range 317-368) and lowest (range 129-316) tertiles, while eGFR was comparable between groups. During follow-up of 15 years, 43 patients developed a macrovascular complication and 26 patients died. In regression analysis, T₅₀ was not a prognostic factor for the development of complications or mortality.

CONCLUSIONS

The T₅₀ time was associated with indices of increased mineral stress, but not with the development of long-term macrovascular complications.

Visceral adipose tissue volume is associated with premature atherosclerosis in early type 2 diabetes mellitus independent of traditional risk factors

BACKGROUND AND AIMS

Type 2 diabetes mellitus (T2DM) is commonly associated with abdominal obesity, predominantly with high visceral adipose tissue (VAT), and is accompanied by premature atherosclerosis. However, the association between VAT and subcutaneous adipose tissue (SAT) with premature atherosclerosis and (i.e. arterial) inflammation is not completely understood. To provide more insight into this association, we investigated the association between arterial ¹⁸F-fluordeoxyglucose (FDG) positron emission tomography (PET) uptake, as a measure of arterial inflammation, and metabolic syndrome (MetS) markers in early T2DM patients.

METHODS

Forty-four patients with early T2DM, without glucose lowering medication, were studied (median age 63 [IQR 54-66] years, median BMI 30.4 [IQR 27.5-35.8]). Arterial inflammation was quantified using glucose corrected maximum standardized uptake value (SUV_max) FDG of the aorta, carotid, iliac, and femoral arteries, and corrected for background activity (blood pool) as target-to-background ratio (_meanTBR). VAT and SAT volumes (cm³) were automatically segmented using computed tomography (CT) between levels L1-L5. Non-alcoholic fatty liver disease (NAFLD) was assessed by liver function test and CT.

RESULTS

VAT volume, but not SAT volume, correlated with _meanTBR (r = 0.325, p = 0.031). Linear regression models showed a significant association, even after sequential adjustment for potentially influencing MetS components. Interaction term VAT volume * sex and additional components including HbA1c, insulin resistance, NAFLD, adiponectin, leptin, and C- reactive protein (CRP) did not change the independent association between VAT volume and _meanTBR.

CONCLUSIONS

CT-assessed VAT volume is positively associated with FDG-PET assessed arterial inflammation, independently of factors thought to potentially mediate these effects. These findings suggest that VAT in contrast to SAT is linked to early atherosclerotic changes in T2DM patients.

18F-sodium fluoride positron emission tomography assessed microcalcifications in culprit and non-culprit human carotid plaques

BACKGROUND

18F-NaF positron emission tomography (PET) targets microcalcifications. We compared in vitro microPET assessed 18F-NaF uptake between culprit and non-culprit human carotid plaques. Furthermore, we compared 18F-NaF uptake with calcification visualized on microcomputed tomography (microCT).

METHODS

Carotid plaques from stroke patients undergoing surgery were incubated in 18F-NaF and scanned using a microPET and a microCT scan. The average PET assessed 18F-NaF uptake was expressed as percentage of the incubation dose per gram (%Inc/g). 18F-NaF PET volume of interest (VOI) was compared with CT calcification VOI.

RESULTS

23 carotid plaques (17 culprit, 6 non-culprit) were included. The average 18F-NaF uptake in culprit carotid plaques was comparable with the uptake in non-culprit carotid plaques (median 2.32 %Inc/g [IQR 1.98 to 2.81] vs. median 2.35 %Inc/g [IQR 1.77 to 3.00], P = 0.916). Only a median of 10% (IQR 4 to 25) of CT calcification VOI showed increased 18F-NaF uptake, while merely a median of 35% (IQR 6 to 42) of 18F-NaF PET VOI showed calcification on CT.

CONCLUSIONS

18F-NaF PET represents a different stage in the calcification process than CT. We observed a similar PET assessed 18F-NaF uptake and pattern in culprit and non-culprit plaques of high-risk patients, indicating that this method may be of more value in early atherosclerotic stenosis development.

Gasotransmitters in health and disease: a mitochondria-centered view

Gasotransmitters fulfill important roles in cellular homeostasis having been linked to various pathologies, including inflammation and cardiovascular diseases. In addition to the known pathways mediating the actions of gasotransmitters, their effects in regulating mitochondrial function are emerging. Given that mitochondria are key organelles in energy production, formation of reactive oxygen species and apoptosis, they are important mediators in preserving health and disease. Preserving or restoring mitochondrial function by gasotransmitters may be beneficial, and mitigate pathogenetic processes. In this review we discuss the actions of gasotransmitters with focus on their role in mitochondrial function and their therapeutic potential.

Urinary Excretion of Sulfur Metabolites and Risk of Cardiovascular Events and All-Cause Mortality in the General Population

Aims: Thiosulfate and sulfate are metabolites of hydrogen sulfide (H₂S), a gaseous signaling molecule with cardiovascular (CV) protective properties. Urinary thiosulfate excretion and sulfate excretion are associated with favorable disease outcome in high-risk patient groups. We investigated the relationship between urinary excretion of sulfur metabolites, and risk of CV events and all-cause mortality in the general population. Results: Subjects (n = 6839) of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study were followed prospectively. At baseline, 24-h urinary excretion of thiosulfate and sulfate was determined. Median urinary thiosulfate and sulfate excretion values were 1.27 (interquartile range [IQR] 0.89-2.37) μmol/24 h and 15.7 (IQR 12.0-20.3) mmol/24 h, respectively. Neither thiosulfate nor sulfate excretion showed an independent association with risk of CV events. Sulfate, but not thiosulfate, was inversely associated with risk of all-cause mortality, independent of potential confounders (hazard ratio 0.73 [95% confidence interval 0.63-0.84], p < 0.001). This association appeared most pronounced for normolipidemic subjects (p_interaction = 0.019). Innovation: The strong association between sulfate excretion and mortality in the general population emphasizes the (patho)physiological importance of sulfate or its precursor H₂S. Conclusion: We hypothesize that urinary sulfate excretion, which is inversely associated with all-cause mortality in the general population, holds clinical relevance as a beneficial modulator in health and disease. Antioxid. Redox Signal. 30, 1999-2010.

Serum free thiols in type 2 diabetes mellitus: A prospective study

•

Serum thiols are a marker of oxidative stress.

•

High serum thiols are associated with better glycemic control and less complications in T2DM.

•

Free thiols have limited capability for the prediction of long-term complications.

Aims

Oxidative stress is a driver in the development of type 2 diabetes (T2DM) complications. As thiols (R-SH) are oxidized by reactive oxygen and sulfur species, circulating concentrations may directly reflect systemic redox status. We hypothesized that high serum R-SH concentrations are a reflection of a favourable redox status and may therefore positively associate with disease status.

Methods

R-SH were measured in serum of 943 T2DM outpatients (55% males, 65 years and HbA1c of 6.7% (50 mmol/mol)) with a follow-up period of 1.2 years.

Results

In the highest R-SH tertile patients were younger, more often men, had less microvascular complications, lower HbA1c and were more often treated nutritionally or with oral glucose-lowering drugs. Age- and sex adjusted hazard ratios for developing micro-, macro- or any complication plus death were 0.994, 0.992 and 0.993: even after adjustment for potential confounders. The Harrell’s C statistic to predict microvascular complications or any complication plus death was higher in the models with R-SH than in those without R-SH.

Conclusions

Although R-SH concentrations were associated with a favourable disease status, it did not add to the predictive capacity for long-term complications. Based on the current data R-SH seems unsuitable as a prognostic marker in T2DM.

Dapagliflozin Attenuates Renal Tubulointerstitial Fibrosis Associated With Type 1 Diabetes by Regulating STAT1/TGFβ1 Signaling

Tubulointerstitial fibrosis (TIF) plays an important role in the progression of renal fibrosis in diabetic nephropathy (DN). Accumulating evidence supports a crucial inhibitory effect of dapagliflozin, a SGLT2 inhibitor, on TIF, but the underlying mechanisms remain largely unknown. This study aimed to shed light on the efficacy of dapagliflozin in reducing TIF as well as its possible impact on renal function. TIF in human kidney biopsies obtained from patients with DN was quantified by histopathological staining. In vitro, HK-2 cells were incubated in high glucose with dapagliflozin or fludarabine, and epithelial-mesenchymal transition (EMT) was determined. In vivo experiments were performed in streptozotocin (STZ)-induced type 1 diabetic mice treated with dapagliflozin by gavage for 16 weeks, after which specific functional characteristics and TIF were analyzed. In both DN patients and diabetic mice, fibronectin and Col IV, as well as STAT1 protein in the kidneys were increased as compared with controls. Dapagliflozin significantly decreased blood glucose, and renal STAT1 and TGF-β1 expression in mice. Furthermore, dapagliflozin improved renal function, and attenuated diabetes-induced TIF. In HK-2 cells, dapagliflozin, and fludarabine directly decreased aberrant STAT1 expression and reversed high glucose-induced downregulation of E-cadherin and α-SMA induction. Thus, the results demonstrate that dapagliflozin not only improves hyperglycemia but also slows down the progression of diabetes-associated renal TIF by improving hyperglycemia-induced activation of the STAT1/TGF-β1 pathway.

Oxidative stress in placental pathology

The most important function of the placenta is the exchange of nutrients and oxygen between a mother and her fetus. To establish a healthy functioning placenta, placentation needs to occur with adequate remodelling of spiral arteries by extravillous trophoblasts. When this process is impaired, the resulting suboptimal and inadequate placenta function results in the manifestation of pregnancy complications. Impaired placenta function can cause preeclampsia and leads to fetal growth restriction due to hypoxia. Presence of hypoxia leads to oxidative stress due to an imbalance between reactive oxygen species and antioxidants, thereby causing damage to proteins, lipids and DNA. In the placenta, signs of morphological adaptation in response to hypoxia can be found. Different placental lesions like maternal or fetal vascular malperfusion or chronic villitis lead to a decreased exchange of oxygen between the mother and the fetus. Clinically, several biomarkers indicative for oxidative stress, e.g. malondialdehyde and reduced levels of free thiols are found. This review aims to give an overview of the causes and (potential) role of placental oxidative stress in the development of placental parenchymal pathology and its clinical consequences. Also, therapeutic options aiming at prevention or treatment of hypoxia of the placenta and fetus are described.

Interferon gamma peptidomimetic targeted to interstitial myofibroblasts attenuates renal fibrosis after unilateral ureteral obstruction in mice

Renal fibrosis cannot be adequately treated since anti-fibrotic treatment is lacking. Interferon-γ is a pro-inflammatory cytokine with anti-fibrotic properties. Clinical use of interferon-γ is hampered due to inflammation-mediated systemic side effects. We used an interferon-γ peptidomimetic (mimγ) lacking the extracellular IFNγReceptor recognition domain, and coupled it to the PDGFβR-recognizing peptide BiPPB. Here we tested the efficacy of mimγ-BiPPB (referred to as “Fibroferon”) targeted to PDGFβR-overexpressing interstitial myofibroblasts to attenuate renal fibrosis without inducing inflammation-mediated side effects in the mouse unilateral ureter obstruction model.

Unilateral ureter obstruction induced renal fibrosis characterized by significantly increased α-SMA, TGFβ1, fibronectin, and collagens I and III protein and/or mRNA expression. Fibroferon treatment significantly reduced expression of these fibrotic markers. Compared to full-length IFNγ, anti-fibrotic effects of Fibroferon were more pronounced. Unilateral ureter obstruction-induced lymphangiogenesis was significantly reduced by Fibroferon but not full-length IFNγ. In contrast to full-length IFNγ, Fibroferon did not induce IFNγ-related side-effects as evidenced by preserved low-level brain MHC II expression (similar to vehicle), lowered plasma triglyceride levels, and improved weight gain after unilateral ureter obstruction.

In conclusion, compared to full-length IFNγ, the IFNγ-peptidomimetic Fibroferon targeted to PDGFβR-overexpressing myofibroblasts attenuates renal fibrosis in the absence of IFNγ-mediated adverse effects.

Tubular maximum phosphate reabsorption capacity in living kidney donors is independently associated with one-year recipient GFR

The donor glomerular filtration rate (GFR) measured before kidney donation is a strong determinant of recipient graft outcome. No tubular function markers have been identified that can similarly be used in donors to predict recipient outcomes. In the present study we investigated whether the pre-donation tubular maximum reabsorption capacity of phosphate (TmP-GFR), which may be considered a functional tubular marker in healthy kidney donors, is associated with recipient GFR at 1 yr after transplantation, a key determinant of long-term outcome. We calculated the pre-donation TmP-GFR from serum and 24-h urine phosphate and creatinine levels in 165 kidney donors, and recipient ¹²⁵I-iothalamate GFR and eGFR (CKD-EPI) at 12 mo after transplantation. Kidney donors were 51 ± 10 yr old, 47% were men, and mean GFR was 118 ± 26 ml/min. The donor TmP-GFR was associated with recipient GFR 12 mo after transplantation (GFR 6.0 ml/min lower per 1 mg/dl decrement of TmP-GFR), which persisted after multivariable adjustment for donor age, sex, pre-donation GFR, and blood pressure and other potential confounders. Results were highly similar when eGFR at 12 mo was taken as the outcome. Tubular damage markers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were low and not associated with recipient GFR. A lower donor TmP-GFR before donation, which may be considered to represent a functional measure of tubular phosphate reabsorption capacity, is independently associated with a lower recipient GFR 1 yr after transplantation. These data are the first to link donor tubular phosphate reabsorption with recipient GFR post-transplantation.

The role of hydrogen sulfide in aging and age-related pathologies

When humans grow older, they experience inevitable and progressive loss of physiological function, ultimately leading to death. Research on aging largely focuses on the identification of mechanisms involved in the aging process. Several proposed aging theories were recently combined as the 'hallmarks of aging'. These hallmarks describe (patho-)physiological processes that together, when disrupted, determine the aging phenotype. Sustaining evidence shows a potential role for hydrogen sulfide (H₂S) in the regulation of aging. Nowadays, H₂S is acknowledged as an endogenously produced signaling molecule with various (patho-) physiological effects. H₂S is involved in several diseases including pathologies related to aging. In this review, the known, assumed and hypothetical effects of hydrogen sulfide on the aging process will be discussed by reviewing its actions on the hallmarks of aging and on several age-related pathologies.

Effects of Klotho on fibrosis and cancer: A renal focus on mechanisms and therapeutic strategies

Klotho is a membrane-bound protein predominantly expressed in the kidney, where it acts as a permissive co-receptor for Fibroblast Growth Factor 23. In its shed form, Klotho exerts anti-fibrotic effects in several tissues. Klotho-deficient mice spontaneously develop fibrosis and Klotho deficiency exacerbates the disease progression in fibrotic animal models. Furthermore, Klotho overexpression or supplementation protects against fibrosis in various models of renal and cardiac fibrotic disease. These effects are mediated at least partially by the direct inhibitory effects of soluble Klotho on TGFβ1 signaling, Wnt signaling, and FGF2 signaling. Soluble Klotho, as present in the circulation, appears to be the primary mediator of anti-fibrotic effects. Similarly, through inhibition of the TGFβ1, Wnt, FGF2, and IGF1 signaling pathways, Klotho also inhibits tumorigenesis. The Klotho promoter gene is generally hypermethylated in cancer, and overexpression or supplementation of Klotho has been found to inhibit tumor growth in various animal models. This review focuses on the protective effects of soluble Klotho in inhibiting renal fibrosis and fibrosis in distant organs secondary to renal Klotho deficiency. We also discuss the structure-function relationships of Klotho domains and biological effects in the context of potential targeted treatment strategies.