A perfusable, vascularized kidney organoid-on-chip model.

The ability to controllably perfuse kidney organoids would better recapitulate the native tissue microenvironment for applications ranging from drug testing to therapeutic use. Here, we report a perfusable, vascularized kidney organoid on chip model composed of two individually addressable channels embedded in an extracellular matrix (ECM). The channels are respectively seeded with kidney organoids and human umbilical vein endothelial cells that form a confluent endothelium (macrovessel). During perfusion, endogenous endothelial cells present within the kidney organoids migrate through the ECM towards the macrovessel, where they form lumen-on-lumen anastomoses that are supported by stromal-like cells. Once micro-macrovessel integration is achieved, we introduced fluorescently labeled dextran of varying molecular weight and red blood cells into the macrovessel, which are transported through the microvascular network to the glomerular epithelia within the kidney organoids. Our approach for achieving controlled organoid perfusion opens new avenues for generating other perfused human tissues.

The REPERFUSE study protocol: The effects of vasopressor therapy on renal perfusion in patients with septic shock-A mechanistically focused randomised control trial.

INTRODUCTION: Acute kidney injury (AKI) is a common complication of septic shock and together these conditions carry a high mortality risk. In septic patients who develop severe AKI, renal cortical perfusion is deficient despite normal macrovascular organ blood flow. This intra-renal perfusion abnormality may be amenable to pharmacological manipulation, which may offer mechanistic insight into the pathophysiology of septic AKI. The aim of the current study is to investigate the effects of vasopressin and angiotensin II on renal microcirculatory perfusion in a cohort of patients with septic shock. METHODS AND ANALYSIS: In this single centre, mechanistically focussed, randomised controlled study, 45 patients with septic shock will be randomly allocated to either of the study vasopressors (vasopressin or angiotensin II) or standard therapy (norepinephrine). Infusions will be titrated to maintain a mean arterial pressure (MAP) target set by the attending clinician. Renal microcirculatory assessment will be performed for the cortex and medulla using contrast-enhanced ultrasound (CEUS) and urinary oxygen tension (pO2), respectively. Renal macrovascular flow will be assessed via renal artery ultrasound. Measurement of systemic macrovascular flow will be performed through transthoracic echocardiography (TTE) and microvascular flow via sublingual incident dark field (IDF) video microscopy. Measures will be taken at baseline, +1 and +24hrs following infusion of the study drug commencing. Blood and urine samples will also be collected at the measurement time points. Longitudinal data will be compared between groups and over time. DISCUSSION: Vasopressors are integral to the management of patients with septic shock. This study aims to further understanding of the relationship between this therapy, renal perfusion and the development of AKI. In addition, using CEUS and urinary pO2, we hope to build a more complete picture of renal perfusion in septic shock by interrogation of the constituent parts of the kidney. Results will be published in peer-reviewed journals and presented at academic meetings. TRIAL REGISTRATION: The REPERFUSE study was registered on Clinical Trials.gov (NCT06234592) on the 30th Jan 24.

The effect of endoscopic renal and ureteral stone surgeries on renal blood flow in children: a prospective trial.

AIM: To assess the impact of endoscopic stone surgeries on renal perfusion and blood flow in children. MATERIALS AND METHODS: Children who underwent percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), ureterorenoscopy (URS), endoscopic combined intrarenal surgery (ECIRS) were included to the study. Renal Doppler ultrasonography (RDUS) was performed one day before the operation, and on the postoperative 1st day and 1st month. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) were measured, and resistive index (RI) was calculated with the (PSV-EDV)/PSV formula. RDUS parameters were compared before and after surgery and between ipsilateral and contralateral kidneys. RESULTS: A total of 45 children with a median age was 8 (2-17) years were included (15 (33.3%) girls, 30 (66.7%) boys). PCNL was performed in 13 children (28.9%), RIRS 11 (24.4%), URS 12 (26.7%), and ECIRS 9 (20%). There was no significant difference in renal and segmental PSV, EDV and RI values of operated kidney in the preoperative, postoperative periods. There was no significant difference between RDUS parameters of the ipsilateral and contralateral kidneys in preoperative or postoperative periods. PSV and EDV values were significantly higher in the 1st postoperative month in the group without preoperative DJ stent than in the group with DJ stent (p = 0,031, p = 0,041, respectively). However, RI values were similar. The mean RI were below the threshold value of 0.7 in each period. CONCLUSION: RDUS parameters didn't show a significant difference in children. Endoscopic surgeries can be safely performed in pediatric stone disease.

Influence of Aortic Arch Morphology on Renal Perfusion in Patients with Coarctation of the Aorta: An Exploratory Study.

Objectives: The configuration of the aortic arch, particularly a Gothic arch shape, in individuals with corrected coarctation of the aorta (CoA) has been associated with a decreased systolic wave amplitude across the arch, which could potentially impair renal perfusion and elevate the risk of arterial hypertension. This study aims to explore the relationship between the morphological characteristics of the aortic arch and their impact on renal perfusion in patients with CoA. Methods: Seventy-one subjects with corrected CoA underwent continuous 24 h ambulatory blood pressure monitoring, computed tomography to assess the aortic arch, and renal perfusion scanning. Subjects were stratified into three groups based on the height-to-width (H/W) ratio of their aortic arch: Group 1 with a H/W ratio of <0.65, Group 2 with a H/W ratio between 0.65 and 0.85, and Group 3 with a H/W ratio of >0.85. Results: Groups 1 and 2 (53,78% and 62.63%) presented with a higher hypertension prevalence of elevated blood pressure than Group 3 (38.89%). Notable variations were observed among the subjects in the time to peak perfusion (Tmax) in the left kidney across the groups. Group 1 showed a median Tmax at 0.27, Group 2 at 0.13, and Group 3 at -0.38 (p-value = 0.079). The differences in Tmax for the right kidney followed a similar trend but were not statistically significant (Group 1 at 0.61, Group 2 at 0.22, and Group 3 at 0.11; p-value = 0.229). Conclusions: This study suggests that variations in the aortic arch morphology might not significantly influence renal perfusion in CoA patients. This indicates the potential adaptability of the renal blood flow, which appears to compensate for reduced perfusion, thus minimizing adverse effects on the kidney function. This adaptability suggests an inherent physiological resilience, emphasizing the need for further targeted research to understand the specific interactions and impacts on treatment strategies for CoA.

Impact of a Single Dose of Alpha-1-Antitrypsin in a Rat Model of Bilateral Kidney Ischemia Reperfusion Injury.

INTRODUCTION: Renal ischemia reperfusion injury is a major cause of perioperative acute kidney injury. Alpha-1-antitrypsin (AAT), a protease inhibitor, might improve outcomes by reducing inflammation and apoptosis. We investigated the effects of a single intravenous dose of AAT immediately before ischemia in a rat bilateral renal clamping model. METHODS: Both renal pedicles of male Sprague-Dawley rats were clamped (45 min). Plasma and renal tissue were collected at 3 h, 24 h, and 7 d. Intravenous AAT (60 mg/kg) was administered 5 min before clamping. Controls received saline. Shams underwent surgery without clamping or injection. Kidney function was assessed by plasma creatinine; injury by aspartate aminotransferase, heart-type-fatty-acid-binding-protein, and histopathology. Renal gene expression of tumor necrosis factor α, interleukin (IL)-6, heat shock protein 70, Chemokine (C-X-C motif) ligand 2, cyclo-oxygenase 2, endothelin-1, IL-10, heme oxygenase 1, B-cell lymphoma 2, and bcl-2-like protein 4 were determined by quantitative reverse transcriptase polymerase chain reaction. RESULTS: None of the 3 h and 24 h end points were different between Control and AAT. In Sham, survival was 100% (6/6), 33% in Control (2/6), and 83% (5/6) in AAT (overall log-rank 0.03). At 7 d, plasma creatinine was lower with higher glomerular filtration rate in surviving AAT treated animals compared to Control (P < 0.001, P 0.03, respectively). These also had lower tumor necrosis factor α and IL-6 gene expression (P 0.001, P < 0.001, respectively). CONCLUSIONS: These data suggest that a single intravenous dose of AAT immediately before ischemia might affect proinflammatory gene expression, glomerular filtration rate and animal survival at 1 wk after reperfusion despite an absence of improvement in early renal function and injury. These findings deserve further investigating in sufficiently powered studies including both sexes.

Modulation of angiopoietin-2 and Tie2: Organ specific effects of microvascular leakage and edema in mice.

INTRODUCTION: Critical illness is associated with organ failure, in which endothelial hyperpermeability and tissue edema play a major role. The endothelial angiopoietin/Tie2 system, a regulator of endothelial permeability, is dysbalanced during critical illness. Elevated circulating angiopoietin-2 and decreased Tie2 receptor levels are reported, but it remains unclear whether they cause edema independent of other critical illness-associated alterations. Therefore, we have studied the effect of angiopoietin-2 administration and/or reduced Tie2 expression on microvascular leakage and edema under normal conditions. METHODS: Transgenic male mice with partial deletion of Tie2 (heterozygous exon 9 deletion, Tie2+/-) and wild-type controls (Tie2+/+) received 24 or 72 pg/g angiopoietin-2 or PBS as control (n = 12 per group) intravenously. Microvascular leakage and edema were determined by Evans blue dye (EBD) extravasation and wet-to-dry weight ratio, respectively, in lungs and kidneys. Expression of molecules related to endothelial angiopoietin/Tie2 signaling were determined by ELISA and RT-qPCR. RESULTS: In Tie2+/+ mice, angiopoietin-2 administration increased EBD extravasation (154 %, p < 0.05) and wet-to-dry weight ratio (133 %, p < 0.01) in lungs, but not in the kidney compared to PBS. Tie2+/- mice had higher pulmonary (143 %, p < 0.001), but not renal EBD extravasation, compared to wild-type control mice, whereas a more pronounced wet-to-dry weight ratio was observed in lungs (155 %, p < 0.0001), in contrast to a minor higher wet-to-dry weight ratio in kidneys (106 %, p < 0.05). Angiopoietin-2 administration to Tie2+/- mice did not further increase pulmonary EBD extravasation, pulmonary wet-to-dry weight ratio, or renal wet-to-dry weight ratio. Interestingly, angiopoietin-2 administration resulted in an increased renal EBD extravasation in Tie2+/- mice compared to Tie2+/- mice receiving PBS. Both angiopoietin-2 administration and partial deletion of Tie2 did not affect circulating angiopoietin-1, soluble Tie2, VEGF and NGAL as well as gene expression of angiopoietin-1, -2, Tie1, VE-PTP, ELF-1, Ets-1, KLF2, GATA3, MMP14, Runx1, VE-cadherin, VEGFα and NGAL, except for gene and protein expression of Tie2, which was decreased in Tie2+/- mice compared to Tie2+/+ mice. CONCLUSIONS: In mice, the microvasculature of the lungs is more vulnerable to angiopoietin-2 and partial deletion of Tie2 compared to those in the kidneys with respect to microvascular leakage and edema.

Angiotensin II Directly Increases Endothelial Calcium and Nitric Oxide in Kidney and Brain Microvessels In Vivo With Reduced Efficacy in Hypertension.

BACKGROUND: The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II-mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo. METHODS AND RESULTS: Changes in VEC intracellular calcium ([Ca2+]i) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5-Salsa6f mice or the endothelial uptake of NO-sensitive dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready-to-use adeno-associated virus expressing Mouse Renin 1 gene (Ren1-AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4-fold increases in VEC [Ca2+]i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5-fold increase in 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II-induced VEC [Ca2+]i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation. CONCLUSIONS: The present study directly visualized angiotensin II-induced increases in VEC [Ca2+]i and NO production that serve to counterbalance agonist-induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium-specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.

miR-486-5p protects against rat ischemic kidney injury and prevents the transition to chronic kidney disease and vascular dysfunction.

AIM: Acute kidney injury (AKI) increases the risk for progressive chronic kidney disease (CKD). MicroRNA (miR)-486-5p protects against kidney ischemia-reperfusion (IR) injury in mice, although its long-term effects on the vasculature and development of CKD are unknown. We studied whether miR-486-5p would prevent the AKI to CKD transition in rat, and affect vascular function. METHODS: Adult male rats were subjected to bilateral kidney IR followed by i.v. injection of liposomal-packaged miR-486-5p (0.5 mg/kg). Kidney function and histologic injury were assessed after 24 h and 10 weeks. Kidney endothelial protein levels were measured by immunoblot and immunofluorescence, and mesenteric artery reactivity was determined by wire myography. RESULTS: In rats with IR, miR-486-5p blocked kidney endothelial cell increases in intercellular adhesion molecule-1 (ICAM-1), reduced neutrophil infiltration and histologic injury, and normalized plasma creatinine (P<0.001). However, miR-486-5p attenuated IR-induced kidney endothelial nitric oxide synthase (eNOS) expression (P<0.05). At 10 weeks, kidneys from rats with IR alone had decreased peritubular capillary density and increased interstitial collagen deposition (P<0.0001), and mesenteric arteries showed impaired endothelium-dependent vasorelaxation (P<0.001). These changes were inhibited by miR-486-5p. Delayed miR-486-5p administration (96 h, 3 weeks after IR) had no impact on kidney fibrosis, capillary density, or endothelial function. CONCLUSION: In rats, administration of miR-486-5p early after kidney IR prevents injury, and protects against CKD development and systemic endothelial dysfunction. These protective effects are associated with inhibition of endothelial ICAM-1 and occur despite reduction in eNOS. miR-486-5p holds promise for the prevention of ischemic AKI and its complications.

Ultra high frequency ultrasound enables real-time visualization of blood supply from chorioallantoic membrane to human autosomal dominant polycystic kidney tissue.

Ultra high frequency (UHF) ultrasound enables the visualization of very small structures that cannot be detected by conventional ultrasound. The utilization of UHF imaging as a new imaging technique for the 3D-in-vivo chorioallantoic membrane (CAM) model can facilitate new insights into tissue perfusion and survival. Therefore, human renal cystic tissue was grafted onto the CAM and examined using UHF ultrasound imaging. Due to the unprecedented resolution of UHF ultrasound, it was possible to visualize microvessels, their development, and the formation of anastomoses. This enabled the observation of anastomoses between human and chicken vessels only 12 h after transplantation. These observations were validated by 3D reconstructions from a light sheet microscopy image stack, indocyanine green angiography, and histological analysis. Contrary to the assumption that the nutrient supply of the human cystic tissue and the gas exchange happens through diffusion from CAM vessels, this study shows that the vasculature of the human cystic tissue is directly connected to the blood vessels of the CAM and perfusion is established within a short period. Therefore, this in-vivo model combined with UHF imaging appears to be the ideal platform for studying the effects of intravenously applied therapeutics to inhibit renal cyst growth.

Dynamic rubidium-82 PET/CT as a novel tool for quantifying hemodynamic differences in renal blood flow using a one-tissue compartment model.

PURPOSE: Assessing renal perfusion in-vivo is challenging and quantitative information regarding renal hemodynamics is hardly incorporated in medical decision-making while abnormal renal hemodynamics might play a crucial role in the onset and progression of renal disease. Combining physiological stimuli with rubidium-82 positron emission tomography/computed tomography (82Rb PET/CT) offers opportunities to test the kidney perfusion under various conditions. The aim of this study is: (1) to investigate the application of a one-tissue compartment model for measuring renal hemodynamics with dynamic 82Rb PET/CT imaging, and (2) to evaluate whether dynamic PET/CT is sensitive to detect differences in renal hemodynamics in stress conditions compared to resting state. METHODS: A one-tissue compartment model for the kidney was applied to cardiac 82Rb PET/CT scans that were obtained for ischemia detection as part of clinical care. Retrospective data, collected from 17 patients undergoing dynamic myocardial 82Rb PET/CT imaging in rest, were used to evaluate various CT-based volumes of interest (VOIs) of the kidney. Subsequently, retrospective data, collected from 10 patients (five impaired kidney functions and five controls) undergoing dynamic myocardial 82Rb PET/CT imaging, were used to evaluate image-derived input functions (IDIFs), PET-based VOIs of the kidney, extraction fractions, and whether dynamic 82Rb PET/CT can measure renal hemodynamics differences using the renal blood flow (RBF) values in rest and after exposure to adenosine pharmacological stress. RESULTS: The delivery rate (K1) values showed no significant (p = 0.14) difference between the mean standard deviation (SD) K1 values using one CT-based VOI and the use of two, three, and four CT-based VOIs, respectively 2.01(0.32), 1.90(0.40), 1.93(0.39), and 1.94(0.40) mL/min/mL. The ratio between RBF in rest and RBF in pharmacological stress for the controls were overall significantly lower compared to the impaired kidney function group for both PET-based delineation methods (region growing and iso-contouring), with the smallest median interquartile range (IQR) of 0.40(0.28-0.66) and 0.96(0.62-1.15), respectively (p < 0.05). The K1 of the impaired kidney function group were close to 1.0 mL/min/mL. CONCLUSIONS: This study demonstrated that obtaining renal K1 and RBF values using 82Rb PET/CT was feasible using a one-tissue compartment model. Applying iso-contouring as the PET-based VOI of the kidney and using AA as an IDIF is suggested for consideration in further studies. Dynamic 82Rb PET/CT imaging showed significant differences in renal hemodynamics in rest compared to when exposed to adenosine. This indicates that dynamic 82Rb PET/CT has potential to detect differences in renal hemodynamics in stress conditions compared to the resting state, and might be useful as a novel diagnostic tool for assessing renal perfusion.

Renal Embolism Associated with the Atrial Myxoma: A Case Report and Literature Review.

Renal embolisms due to cardiac myxomas are extremely rare; the clinical course, treatment, and prognosis of this disease are not established. A 69-year-old Japanese woman who underwent a nephrectomy for renal cell carcinoma 3 years earlier was hospitalized with a right occipital lobe cerebral infarction. Her renal function suddenly worsened 3 days post-admission: her serum creatinine rose from 1.46 mg/dL to 6.57 mg/dL and then to 8.03 mg/dL the next day, and hemodialysis therapy was started. Abdominal computed tomography (CT) scans showed patchy non-contrasted low-density areas in the right kidney, and chest CT scans and transesophageal ultrasonography revealed a left atrial tumor. We diagnosed renal infarction due to a left atrial myxoma. Hemodialysis and anticoagulant therapy (heparin) were continued, followed by the cardiac myxoma's resection. The patient's renal function gradually improved post-surgery, and the hemodialysis was discontinued. Considering our patient and 19 other case reports of renal infarction associated with cardiac myxoma, the treatment for such a renal infarction and the outcomes differ depending on the embolus site. The poor outcome of abdominal aortic embolism requires a prompt embolectomy, whereas a branch renal artery embolism requires anticoagulation therapy to prevent thrombosis formation around the myxoma.

MELATONIN ATTENUATES RENAL ISCHEMIA-REPERFUSION INJURY BY REGULATING MITOCHONDRIAL DYNAMICS AND AUTOPHAGY THROUGH AMPK/DRP1.

ABSTRACT: Ischemia-reperfusion injury (IRI) often stems from an imbalance between mitochondrial dynamics and autophagy. Melatonin mitigates IRI by regulating mitochondrial dynamics. However, the precise molecular mechanism underlying the role of melatonin in reducing IRI through modulating mitochondrial dynamics remains elusive. The objective of this study was to investigate whether pretreatment with melatonin before IRI confers protective effects by modulating mitochondrial dynamics and mitophagy. Melatonin pretreatment was administered to HK-2 cells and live rats before subjecting them to hypoxia-reoxygenation or IRI, respectively. Cells and rat kidney models were evaluated for markers of oxidative stress, autophagy, mitochondrial dynamics, and the expression of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and phospho-AMPKα (P-AMPK). After renal IRI, increased mitochondrial fission and autophagy were observed, accompanied by exacerbated cellular oxidative stress injury and aggravated mitochondrial dysfunction. Nevertheless, melatonin pretreatment inhibited mitochondrial fission, promoted mitochondrial fusion, and attenuated autophagy levels. This intervention was correlated with a notable reduction in oxidative stress injury and remarkable restoration of mitochondrial functionality. Ischemia-reperfusion injury led to a decline in P-AMPK levels, whereas melatonin pretreatment increased the level of P-AMPK levels. Silencing AMPK with small interfering RNA exacerbated mitochondrial damage, and in this context, melatonin pretreatment did not alleviate mitochondrial fission or autophagy levels but resulted in sustained oxidative stress damage. Collectively, these findings indicate that melatonin pretreatment shields the kidneys from IRI by mitigating excessive mitochondrial fission, moderating autophagy levels, and preserving appropriate mitochondrial fission, all in an AMPK-dependent manner.

The prevalence of accessory renal arteries in sudanese population in Khartoum State: a cross-sectional CT study from 2017 to 2020.

BACKGROUND: Renal artery variations are clinically significant due to their implications for surgical procedures and renal function. However, data on these variations in Sudanese populations are limited. This study aimed to determine the prevalence and characteristics of renal artery variations in a Sudanese population. METHODS: A cross-sectional retrospective study was conducted in Khartoum state from October 2017 to October 2020. A total of 400 Sudanese participants who underwent abdominal CT scans were included. Data on demographic characteristics, kidney measurements, and renal vasculature were collected and analyzed using descriptive statistics and inferential tests. RESULTS: The mean age of participants was 46.7 ± 18 years, with a nearly equal gender distribution. Overall, renal artery variations were present in 11% of participants, with accessory renal arteries observed in 6% of the study population. Among those with accessory vessels, 50% were on the right side, 29.2% on the left, and 20.8% bilateral, distributed across hilar 29.2%, lower polar 29.2%, and upper polar 41.7% regions. No significant associations were found between accessory renal arteries and age or gender (p-value > 0.05). However, participants with accessory renal arteries exhibited significantly narrower width 5.0 ± 1.4 than those with no with accessory renal arteries 5.8 ± 1.1 (p-value 0.002) Early dividing renal arteries were found in 5% of participants, with nearly half being bilateral. No significant associations were found between the presence of early dividing renal arteries and demographic or renal measurements (p-value > 0.05). CONCLUSION: This study provides valuable insights into the prevalence and characteristics of renal artery variations in a Sudanese population. The findings contribute to our understanding of renal anatomy in this demographic and can inform clinical practice and surgical planning, particularly in renal transplantation and other renal procedures.

Sepsis induces heterogeneous transcription of coagulation- and inflammation-associated genes in renal microvasculature.

BACKGROUND: Acute kidney injury (AKI) in sepsis patients increases patient mortality. Endothelial cells are important players in the pathophysiology of sepsis-associated AKI (SA-AKI), yet knowledge regarding their spatiotemporal involvement in coagulation disbalance and leukocyte recruitment is lacking. This study investigated the identity and kinetics of responses of different microvascular compartments in kidney cortex in response to SA-AKI. METHODS: Laser microdissected arterioles, glomeruli, peritubular capillaries, and postcapillary venules from kidneys of mice subjected to cecal ligation and puncture (CLP) were analyzed using RNA sequencing. Differential expression and pathway enrichment analyses identified genes involved in coagulation and inflammation. A selection of these genes was evaluated by RT-qPCR in microvascular compartments of renal biopsies from patients with SA-AKI. The role of two identified genes in lipopolysaccharide-induced endothelial coagulation and inflammatory activation were determined in vitro in HUVEC using siRNA-based gene silencing. RESULTS: CLP-sepsis in mice induced altered expression of approximately 400 genes in the renal microvasculature, with microvascular compartments exhibiting unique spatiotemporal responses. In mice, changes in gene expression related to coagulation and inflammation were most extensive in glomeruli at early and intermediate time points, with high induction of Plat, Serpine1, Thbd, Icam1, Stat3, and Ifitm3. In human SA-AKI, PROCR and STAT3 were induced in postcapillary venules, while SERPINE1 expression was diminished. IFITM3 was increased in arterioles and glomeruli. In vitro studies revealed that STAT3 and IFITM3 partly control endothelial coagulation and inflammatory activation. CONCLUSION: Renal microvascular compartments in mice and humans exhibited heterogeneous changes in coagulation- and inflammation-related gene expression in response to SA-AKI. Additional research should aim at understanding the functional consequences of the here described heterogeneous microvascular responses to establish the usefulness of identified genes as therapeutic targets in SA-AKI.

Inhibition of Usp14 ameliorates renal ischemia-reperfusion injury by reducing Tfap2a stabilization and facilitating mitophagy.

Mitochondrial dysfunction is recognized as a pivotal contributor to the pathogenesis of renal ischemia-reperfusion (IR) injury. Mitophagy, the process responsible for removing damaged protein aggregates, stands as a critical mechanism safeguarding cells against IR injury. Currently, the role of deubiquitination in regulating mitophagy still needs to be completely elucidated. This study aimed to evaluate the impact of ubiquitin-specific peptidase 14 (Usp14), a deubiquitinase, in IR injury by influencing mitophagy. Utilizing a murine model of renal IR injury, Usp14 silencing was found to ameliorate kidney injury, leading to decreased levels of serum creatinine and blood urea nitrogen, alongside diminished oxidative stress and inflammation. In renal epithelial cells subjected to hypoxia/reoxygenation (H/R), Usp14 knockdown increased cell viability and reduced apoptosis. Further mechanistic studies revealed that Usp14 interacted with and deubiquitinated transcription factor AP-2 alpha (Tfap2a), thereby suppressing its downstream target gene, TANK binding kinase 1 (Tbk1), to influence mitophagy. Tfap2a overexpression or Tbk1 inhibition reversed the protective effects of Usp14 silencing on renal tubular cell injury and its facilitation of mitophagy. In summary, our study demonstrated the renoprotective role of Usp14 knockdown in mitigating renal IR injury by promoting Tfap2a-mediated Tbk1 upregulation and mitophagy. These findings advocate for exploring Usp14 inhibition as a promising therapeutic avenue for mitigating IR injury, primarily by enhancing the clearance of damaged mitochondria through augmented mitophagy.

[Update kidney allograft pathology : A better depiction of microvascular inflammation]. / Update Nierentransplantationspathologie : Eine bessere Darstellung der mikrovaskulären Entzündung.

BACKGROUND: The Banff Foundation produces recommendations for classifying various lesions in renal allografts. Experts gather to update the classification every other year based on new scientific and clinical evidence. OBJECTIVES: This article presents the most important changes incorporated into the new recommendations after the last Banff conference. MATERIALS AND METHODS: The author of this article personally took part in the Banff conference and the subsequent survey, reported on the activities of a Banff working group (peritubular capillaritis) on-site, and contributed to drafting the recently published meeting report. RESULTS: Lesions of antibody-mediated kidney allograft rejection (AMR), especially microvascular inflammation, have been part of the diagnostic algorithm for over 20 years. Experts advocated for a simplified AMR algorithm and mindful inclusion of molecular pathological data in the clinicopathological reflection regarding therapeutic decision. A new, more descriptive diagnostic entity-microvascular inflammation, C4d negative and DSA negative-has been introduced into the AMR category to acknowledge this histological constellation and motivate research into this pathophysiologically and immunologically probably different phenotype. CONCLUSIONS: The Banff classification provides a structure for diagnosing kidney transplant pathology. Regular updates serve to adapt to ever-growing knowledge about alloimmunity. Particular challenges are capturing the complexity of various immunological scenarios and ensuring an understandable representation of these in a pathology report.

Tissue-resident Lymphocytes Are Released During Hypothermic and Normothermic Machine Perfusion of Human Donor Kidneys.

BACKGROUND: Machine perfusion is the preferred preservation method for deceased donor kidneys. Perfusate fluid, which contains a complex mixture of components, offers potential insight into the organ's viability and function. This study explored immune cell release, particularly tissue-resident lymphocytes (TRLs), during donor kidney machine perfusion and its correlation with injury markers. METHODS: Perfusate samples from hypothermic machine perfusion (HMP; n = 26) and normothermic machine perfusion (NMP; n = 16) of human donor kidneys were analyzed for TRLs using flow cytometry. Residency was defined by expressions of CD69, CD103, and CD49as. TRL release was quantified exclusively in NMP. Additionally, levels of cell-free DNA, neutrophil gelatinase-associated lipocalin, and soluble E-cadherin (sE-cadherin) were measured in NMP supernatants with quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. RESULTS: Both HMP and NMP samples contained a heterogeneous population of TRLs, including CD4 + tissue-resident memory T cells, CD8 + tissue-resident memory T cells, tissue-resident natural killer cells, tissue-resident natural killer T cells, and helper-like innate lymphoid cells. Median TRL proportions among total CD45 + lymphocytes were 0.89% (NMP) and 0.84% (HMP). TRL quantities in NMP did not correlate with donor characteristics, perfusion parameters, posttransplant outcomes, or cell-free DNA and neutrophil gelatinase-associated lipocalin concentrations. However, CD103 + TRL release positively correlated with the release of sE-cadherin, the ligand for the CD103 integrin. CONCLUSIONS: Human donor kidneys release TRLs during both HMP and NMP. The release of CD103 + TRLs was associated with the loss of their ligand sE-cadherin but not with general transplant injury biomarkers.