MRgFUS ablation of a recurrent tenosynovial giant cell tumor in the foot using ExAblate 2100 system in combination with patient immobilization device

INTRODUCTION

Magnetic Resonance-guided Focused Ultrasound (MRgFUS) treatment for certain anatomy locations can be extremely challenging due to patient positioning and potential motion. This present study describes the treatment of a recurrent tenosynovial giant cell tumor of the plantar forefoot using the ExAblate 2100 system in combination with patient immobilization device.

METHODS

Prior to the treatment, several patient immobilization devices were investigated. Vacuum cushions were selected and tested for safety and compatibility with the treatment task and the MR environment.

RESULTS

During the treatment, one vacuum cushion immobilized the patient's right leg in knee flexion and allowed the bottom of the foot to be securely positioned on the treatment window. Another vacuum cushion supported the patient upper body extended outside the scanner bore. 19 sonications were successfully executed. The treatment was judged to be successful. No immediate complications were observed.

CONCLUSIONS

MRgFUS treatment of a recurrent tenosynovial giant cell tumor of the right plantar forefoot was successful with the use of patient immobilization vacuum cushions.

IMPLICATIONS FOR PRACTICE

The immobilization system could be utilized to aid future MRgFUS treatment of lesions in challenging anatomic locations. Various sizes of the vacuum cushions are available to potentially better accommodate other body parts and treatment configurations.

[Literature data mining on the current research status of uveitis in China]

Objective: To analyze the current research status of uveitis in China. Methods: It was a bibliometric analysis study. Using search formulas covering uveitis and its multiple subtypes, uveitis-related literature in English with publication dates from 2013 to 2022 was retrieved in Web of Science core databases through certain search strategies. This study used the latent Dirichlet allocation (LDA) algorithm to build topic models and analyzed the trends of research topics in recent years. Bibliometric analysis was used to analyze and visualize the bibliometric indicators (e.g., number of publications, citations, and H-index) of the included literature using tools such as VOSviewer software. Results: Over the past decade, China has published 1 657 papers on uveitis, ranking second globally. However, there is still room for improvement in terms of the H-index (58) and citation (12.28 per publication). Countries such as the USA (43.04%) and the United Kingdom (62.54%) were engaged in more international collaboration. We identified ten optimal LDA topics for uveitis literature in China such as immunotherapy, Behçet's disease, and Vogt-Koyanagi-Harada syndrome. Research on uveitis in China was mostly published in Ocular Immunology and Inflammation (92). Conclusions: China has made remarkable progress in uveitis research. Nonetheless, there is still untapped potential to enhance our global academic influence. It is encouraged to promote international collaborations, harness our expertise in areas like Behçet's disease and VKH syndrome, and publish our scientific achievements in high-impact journals.

Uncertainties and opportunities in delivering environmentally sustainable surgery: the surgeons' view

Surgery is a carbon-heavy activity and creates a high volume of waste. Surgical teams around the world want to deliver more environmentally sustainable surgery but are unsure what to do and how to create change. There are many interventions available, but resources and time are limited. Capital investment into healthcare and engagement of senior management are challenging. However, frontline teams can change behaviours and drive wider change. Patients have a voice here too, as they would like to ensure their surgery does not harm their local community but are concerned about the effects on them when changes are made. Environmentally sustainable surgery is at the start of its journey. Surgeons need to rapidly upskill their generic knowledge base, identify which measures they can implement locally and take part in national research programmes. Surgical teams in the NHS have the chance to create a world-leading programme that can bring change to hospitals around the world. This article provides an overview of how surgeons see the surgical team being involved in environmentally sustainable surgery.

A pilot study to assess the impact of aboriginal and torres strait islander cultural humility webinars on australian medical school students

BACKGROUND

The Aboriginal and Torres Strait Islander Health Curriculum Framework helps higher education providers to deliver safe and well-informed cultural humility education. However, there is currently a scarcity of evidence surrounding the efficacy and impact of cultural humility education. This study will use qualitative and quantitative research methods to evaluate learning outcomes from an Indigenous health educational webinar aimed at Australian medical students.

METHODS

A pilot study was conducted following a group of Australian medical students who attended an educational Indigenous health (IH) culturally responsive webinar. Recruitment was conducted via the webinar hosts' social media pages. Quantitative methods involved sending one pre- and two post-webinar questionnaires to attendees. To assess participants' retention of information, one post-webinar survey was sent out immediately after the webinar and another three months after the webinar. These questionnaires were designed to reflect pre-determined learning objectives for the webinar. Qualitative methods involved a focus group discussion to identify common themes from participant feedback.

RESULTS

Twenty-six participants were included in the final quantitative analysis. Most of the participants were clinical students between 18 and 24 years old who did not identify as Aboriginal and/or Torres Strait Islander. There was a significant increase (p = 0.007) between pre-intervention (M = 0.35, SD = 0.26) and post-webinar knowledge for the learning outcome exploring the links between health and education (M = 047, SD = 0.25). No results were obtained from the three months post-intervention questionnaire. The qualitative analysis synthesized feedback from three participants and identified presenter delivery style as an important mediator of webinar effectiveness.

CONCLUSIONS

There was a significant increase in knowledge and understanding for the learning outcome that explored the links between health and education. We attribute this partly to the engaging and conversational delivery style of the webinar presenters. The importance of Indigenous facilitators that encourage reflective teaching should not be understated. Our results suggest that cultural humility webinars can have a positive impact on medical students' understanding of the Aboriginal and/or Torres Strait Islander health landscape. This pilot study warrants further research on a larger population.

The SPEAK study rationale and design: A linguistic corpus-based approach to understanding thought disorder

AIM

Psychotic symptoms are typically measured using clinical ratings, but more objective and sensitive metrics are needed. Hence, we will assess thought disorder using the Research Domain Criteria (RDoC) heuristic for language production, and its recommended paradigm of "linguistic corpus-based analyses of language output". Positive thought disorder (e.g., tangentiality and derailment) can be assessed using word-embedding approaches that assess semantic coherence, whereas negative thought disorder (e.g., concreteness, poverty of speech) can be assessed using part-of-speech (POS) tagging to assess syntactic complexity. We aim to establish convergent validity of automated linguistic metrics with clinical ratings, assess normative demographic variance, determine cognitive and functional correlates, and replicate their predictive power for psychosis transition among at-risk youths.

METHODS

This study will assess language production in 450 English-speaking individuals in Australia and Canada, who have recent onset psychosis, are at clinical high risk (CHR) for psychosis, or who are healthy volunteers, all well-characterized for cognition, function and symptoms. Speech will be elicited using open-ended interviews. Audio files will be transcribed and preprocessed for automated natural language processing (NLP) analyses of coherence and complexity. Data analyses include canonical correlation, multivariate linear regression with regularization, and machine-learning classification of group status and psychosis outcome.

CONCLUSIONS

This prospective study aims to characterize language disturbance across stages of psychosis using computational approaches, including psychometric properties, normative variance and clinical correlates, important for biomarker development. SPEAK will create a large archive of language data available to other investigators, a rich resource for the field.

Medical Imaging Compatibility of Magnesium- and Iron-Based Bioresorbable Flow Diverters

BACKGROUND AND PURPOSE

Bioresorbable flow diverters are under development to mitigate complications associated with conventional flow-diverter technology. One proposed advantage is the ability to reduce metal-induced artifacts in follow-up medical imaging. In the current work, the medical imaging compatibility of magnesium- and iron-based bioresorbable flow diverters is assessed relative to an FDA-approved control in phantom models.

MATERIALS AND METHODS

Bioresorbable flow diverters, primarily composed of braided magnesium or antiferromagnetic iron alloy wires, were compared with an FDA-approved control flow diverter. The devices were assessed for MR imaging safety in terms of magnetically induced force and radiofrequency heating using 1.5T, 3T, and 7T field strength clinical scanners. The devices were deployed in phantom models, and metal-induced image artifacts were assessed in the 3 MR imaging scanners and a clinical CT scanner following clinical scan protocols; device visibility was assessed under fluoroscopy.

RESULTS

The magnesium-based bioresorbable flow diverter, iron-based bioresorbable flow diverter, and the control device all demonstrated MR imaging safety in terms of magnetically induced force and radiofrequency heating at all 3 field strengths. The bioresorbable flow diverters did not elicit excessive MR imaging artifacts at any field strength relative to the control. Furthermore, the bioresorbable flow diverters appeared to reduce blooming artifacts in CT relative to the control. The iron-based bioresorbable flow diverter and control device were visible under standard fluoroscopy.

CONCLUSIONS

We have demonstrated the baseline medical imaging compatibility of magnesium and antiferromagnetic iron alloy bioresorbable flow diverters. Future work will evaluate the medical imaging characteristics of the bioresorbable flow diverters in large-animal models.

Quercetin downregulates the expression of IL15 in cancer cells through DNA methylation

OBJECTIVE

This study aimed to investigate the effect of quercetin on cellular immunity (via IL15 expression) against cancer and to elucidate its regulatory mechanism.

MATERIALS AND METHODS

HeLa cells and A549 cells were cultured in vitro and were divided into control (DMSO treated) and experimental groups (treated with different concentrations of quercetin). Transcript levels of IL15 and DNA methyltransferase (DNMTS) were measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Genomic DNA was extracted, treated with bisulfite, and the promoter region of IL15 was cloned. Finally, Sanger sequencing was used to detect the degree of promoter methylation.

RESULTS

Following quercetin treatment, the expression of IL15 was significantly downregulated in HeLa and A549 cells. The methylation level of IL15 promoter in HeLa cells was about twice that of the control group, and the methylation level of IL15 promoter in A549 cells was about three times that of the control group.

CONCLUSIONS

Quercetin inhibits cancer cell proliferation while downregulating IL15 expression, and this regulation is achieved by increasing the methylation of the IL15 promoter.

Multi-Stage Adaptive Spline Autofocus (MASA) with a Learned Metric for Deformable Motion Compensation in Interventional Cone-Beam CT

Purpose

Cone-beam CT (CBCT) is widespread in abdominal interventional imaging, but its long acquisition time makes it susceptible to patient motion. Image-based autofocus has shown success in CBCT deformable motion compensation, via deep autofocus metrics and multi-region optimization, but it is challenged by the large parameter dimensionality required to capture intricate motion trajectories. This work leverages the differentiable nature of deep autofocus metrics to build a novel optimization strategy, Multi-Stage Adaptive Spine Autofocus (MASA), for compensation of complex deformable motion in abdominal CBCT.

Methods

MASA poses the autofocus problem as a multi-stage adaptive sampling strategy of the motion trajectory, sampled with Hermite spline basis with variable amplitude and knot temporal positioning. The adaptive method permits simultaneous optimization of the sampling phase, local temporal sampling density, and time-dependent amplitude of the motion trajectory. The optimization is performed in a multi-stage schedule with increasing number of knots that progressively accommodates complex trajectories in late stages, preconditioned by coarser components from early stages, and with minimal increase in dimensionality. MASA was evaluated in controlled simulation experiments with two types of motion trajectories: i) combinations of slow drifts with sudden jerk (sigmoid) motion; and ii) combinations of periodic motion sources of varying frequency into multi-frequency trajectories. Further validation was obtained in clinical data from liver CBCT featuring motion of contrast-enhanced vessels, and soft-tissue structures.

Results

The adaptive sampling strategy provided successful motion compensation in sigmoid trajectories, compared to fixed sampling strategies (mean SSIM increase of 0.026 compared to 0.011). Inspection of the estimated motion showed the capability of MASA to automatically allocate larger sampling density to parts of the scan timeline featuring sudden motion, effectively accommodating complex motion without increasing the problem dimension. Experiments on multi-frequency trajectories with 3-stage MASA (5, 10, and 15 knots) yielded a twofold SSIM increase compared to single-stage autofocus with 15 knots (0.076 vs 0.040, respectively). Application of MASA to clinical datasets resulted in simultaneous improvement on the delineation of both contrast-enhanced vessels and soft-tissue structures in the liver.

Conclusion

A new autofocus framework, MASA, was developed including a novel multi-stage technique for adaptive temporal sampling of the motion trajectory in combination with fully differentiable deep autofocus metrics. This novel adaptive sampling approach is a crucial step for application of deformable motion compensation to complex temporal motion trajectories.

3D-2D image registration in the presence of soft-tissue deformation in image-guided transbronchial interventions

Purpose. Target localization in pulmonary interventions (e.g. transbronchial biopsy of a lung nodule) is challenged by deformable motion and may benefit from fluoroscopic overlay of the target to provide accurate guidance. We present and evaluate a 3D-2D image registration method for fluoroscopic overlay in the presence of tissue deformation using a multi-resolution/multi-scale (MRMS) framework with an objective function that drives registration primarily by soft-tissue image gradients.Methods. The MRMS method registers 3D cone-beam CT to 2D fluoroscopy without gating of respiratory phase by coarse-to-fine resampling and global-to-local rescaling about target regions-of-interest. A variation of the gradient orientation (GO) similarity metric (denotedGO') was developed to downweight bone gradients and drive registration via soft-tissue gradients. Performance was evaluated in terms of projection distance error at isocenter (PDE_iso). Phantom studies determined nominal algorithm parameters and capture range. Preclinical studies used a freshly deceased, ventilated porcine specimen to evaluate performance in the presence of real tissue deformation and a broad range of 3D-2D image mismatch.Results. Nominal algorithm parameters were identified that provided robust performance over a broad range of motion (0-20 mm), including an adaptive parameter selection technique to accommodate unknown mismatch in respiratory phase. TheGO'metric yielded median PDE_iso= 1.2 mm, compared to 6.2 mm for conventionalGO.Preclinical studies with real lung deformation demonstrated median PDE_iso= 1.3 mm with MRMS +GO'registration, compared to 2.2 mm with a conventional transform. Runtime was 26 s and can be reduced to 2.5 s given a prior registration within ∼5 mm as initialization.Conclusions. MRMS registration via soft-tissue gradients achieved accurate fluoroscopic overlay in the presence of deformable lung motion. By driving registration via soft-tissue image gradients, the method avoided false local minima presented by bones and was robust to a wide range of motion magnitude.

Space-time analysis of COVID-19 cases and SARS-CoV-2 wastewater loading: A geodemographic perspective

Severe acute respiratory syndrome - coronavirus 2 (SARS-CoV-2) continues to effect communities across the world. One way to combat these effects is to enhance our collective ability to remotely monitor community spread. Monitoring SARS-CoV-2 in wastewater is one approach that enables researchers to estimate the total number of infected people in a region; however, estimates are often made at the sewershed level which may mask the geographic nuance required for targeted interdiction efforts. In this work, we utilize an apportioning method to compare the spatial and temporal trends of daily case count with the temporal pattern of viral load in the wastewater at smaller units of analysis within Austin, TX. We find different lag-times between wastewater loading and case reports. Daily case reports for some locations follow the temporal trend of viral load more closely than others. These findings are then compared to socio-demographic characteristics across the study area.

(Pro)renin Receptor Regulates Phosphate Homeostasis in Rats via Releasing Fibroblast Growth Factor-23

Phosphate (Pi) is one of the basic necessities required for sustenance of life and its metabolism largely relies on excretory function of the kidney, a process chiefly under the endocrine control of bone-derived fibroblast growth factor 23 (FGF23). However, knowledge gap exists in understanding the regulatory loop responsible for eliciting phophaturic response to Pi treatment. Here, we reported a novel role of (pro)renin receptor (PRR) in mediating phosphaturic response to Pi treatment via upregulation of FGF23 production. Male Sprague-Dawley rats were pretreated for 5 days via osmotic pump-driven infusion of a PRR antagonist PRO20 or vehicle, and then treated with high Pi (HP) solution as drinking fluid for the last 24 h. PRO20 reduced HP-induced Pi excretion by 42%, accompanied by blunted upregulation of circulating FGF23 and parathyroid hormone (PTH) and downregulation of renal Na/Pi-IIa expression. In cultured osteoblast cells, exposure to HP induced a 1.56-fold increase in FGF23 expression, which was blunted by PRO20 or siRNA against PRR. Together, these results suggest that activation of PRR promotes phosphaturic response through stimulation of FGF23 production and subsequent downregulation of renal Na/Pi-IIa expression.

Targeted Deformable Motion Compensation for Vascular Interventional Cone-Beam CT Imaging

Purpose

Cone-beam CT has become commonplace for 3D guidance in interventional radiology (IR), especially for vascular procedures in which identification of small vascular structures is crucial. However, its long image acquisition time poses a limit to image quality due to soft-tissue deformable motion that hampers visibility of small vessels. Autofocus motion compensation has shown promising potential for soft-tissue deformable motion compensation, but it lacks specific target to the imaging task. This work presents an approach for deformable motion compensation targeted at imaging of vascular structures.

Methods

The proposed method consists on a two-stage framework for: i) identification of contrast-enhanced blood vessels in 2D projection data and delineation of an approximate region covering the vascular target in the volume space, and, ii) a novel autofocus approach including a metric designed to promote the presence of vascular structures acting solely in the region of interest. The vesselness of the image is quantified via evaluation of the properties of the 3D image Hessian, yielding a vesselness filter that gives larger values to voxels candidate to be part of a tubular structure. A cost metric is designed to promote large vesselness values and spatial sparsity, as expected in regions of fine vascularity. A targeted autofocus method was designed by combining the presented metric with a conventional autofocus term acting outside of the region of interest. The resulting method was evaluated on simulated data including synthetic vascularity merged with real anatomical features obtained from MDCT data. Further evaluation was obtained in two clinical datasets obtained during TACE procedures with a robotic C-arm (Artis Zeego, Siemens Healthineers).

Results

The targeted vascular autofocus effectively restored the shape and contrast of the contrast-enhanced vascularity in the simulation cases, resulting in improved visibility and reduced artifacts. Segmentations performed with a single threshold value on the target vascular regions yielded a net increase of up to 42% in DICE coefficient computed against the static reference. Motion compensation in clinical datasets resulted in improved visibility of vascular structures, observed in maximum intensity projections of the contrast-enhanced liver vessel tree.

Conclusion

Targeted motion compensation for vascular imaging showed promising performance for increased identification of small vascular structures in presence of motion. The development of autofocus metrics and methods tailored to vascular imaging opens the way for reliable compensation of deformable motion while preserving the integrity of anatomical structures in the image.

Role of (Pro)Renin Receptor in Cyclosporin A-Induced Nephropathy

Calcineurin inhibitors (CNIs) such as cyclosporin A (CsA) have been widely used to improve graft survival following solid-organ transplantation. However, the clinical use of CsA is often limited by its nephrotoxicity. The present study tested the hypothesis that activation of (pro)renin receptor (PRR) contributes to CsA-induced nephropathy by activating the renin-angiotensin system (RAS). Renal injury in male Sprague-Dawley rats was induced by a low-salt diet combined with CsA as evidenced by elevated plasma creatinine and BUN levels, decreased creatinine clearance and induced renal inflammation, apoptosis as well as interstitial fibrosis, elevated urinary N-acetyl-β-D-glucosaminidase activity and urinary kidney injury molecular 1 content. Each index of renal injury was attenuated following a 2-wk treatment with a PRR decoy inhibitor PRO20. While CsA rats with kidney injury displayed increased renal sPRR abundance, plasma sPRR, renin activity, Ang II, and heightened urinary total prorenin/renin content; RAS activation was attenuated by PRO20. Exposure of cultured human renal proximal tubular HK-2 cells to CsA induced expression of fibronectin and sPRR production, but the fibrotic response was attenuated by PRO20 and siRNA-mediated PRR knockdown. These findings support the hypothesis that activation of PRR contributes to CsA-induced nephropathy by activating the RAS in rats. Of importance, we provide strong proof of concept that targeting PRR offers a novel therapeutic strategy to limit nephotoxic effects of immunosuppressant drugs.

[The mechanism of circ_0023990/miR-873-5p/ANXA2 axis regulating radiosensitivity and development of thyroid carcinoma]

Objective: To explore the effect and possible mechanism of circ_0023990 on the radiosensitivity of thyroid cancer cells. Methods: qRT-PCR was used to detect the expression of circ_0023990 in the cancer tissues of 55 patients with thyroid cancer and thyroid cancer cell lines (TPC-1, KTC-1, FTC-133 and CAL-62), and the relationship between the expression of circ_0023990 in cancer tissues and the clinical characteristics of the patients were analyzed. Thyroid cancer cells TPC-1 and KTC-1 were divided into sh-circ_0023990 group, sh-NC group, sh-circ_0023990+anti-miR-873-5p group, sh-circ_0023990+anti-miR-NC group, miR-873-5p group, miR-NC group, miR-873-5p+pcDNA-ANXA2 group and miR-873-5p+pcDNA group, and then clone formation experiment was used to detect cell radiosensitivity. After each group of cells was irradiated with 4Gy radiation, the expression of γH2AX protein in the cells was detected by Western Blot. The dual luciferase reporter gene experiment verified the targeting relationship between circ_0023990 and miR-873-5p or miR-873-5p and ANXA2. Results: The expression of circ_0023990 in thyroid cancer tissues was higher than that in normal tissues (2.15±0.09 vs. 0.97±0.05, P<0.05), and its expression was closely related to tumor size, lymph node metastasis and TNM staging of patients with thyroid cancer (P<0.05). The expression of circ_0023990 in thyroid cancer cell lines (TPC-1, KTC-1, FTC-133 and CAL-62) were higher than that of normal thyroid cells HTori-3 (3.16±0.38, 2.63±0.28, 1.82±0.24, 1.71±0.22 vs. 1.00±0.10, all P<0.05). The survival scores of TPC-1 and KTC-1 cells in the sh-circ_0023990 group were significantly lower than those in the sh-NC group (P<0.05), and the sensitization ratios were 2.482, 1.643; The survival scores of TPC-1 and KTC-1 cells in the sh-circ_0023990+anti-miR-873-5p group were higher than those in the sh-circ_0023990+anti-miR-NC group (P<0.05), and the sensitization ratios were 0.305, 0.441, respectively. The survival scores of TPC-1 and KTC-1 cells in the miR-873-5p group were lower than those in the miR-NC group (P<0.05), and the sensitization ratios were 2.044, 1.653 respectively. The survival scores of TPC-1 and KTC-1 cells in the miR-873-5p+pcDNA-ANXA2 group was higher than that in the miR-873-5p+pcDNA group (P<0.05), and the sensitization ratios were 0.496, 0.686, respectively. The expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+sh-circ_0023990 group were higher than that in the 4 Gy+sh-NC group (2.68±0.27 vs. 1.87±0.25, 2.46±0.19 vs. 1.77±0.14; all P<0.05), but the expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+sh-circ_0023990+anti-miR-873-5p group were lower than that in the 4 Gy+sh-circ_0023990+anti-miR-NC group (1.13±0.09 vs. 1.69±0.09, 1.11±0.08 vs. 1.60±0.08; both P<0.05). The expression of γH2AX protein in TPC-1 and KTC-1 cells in the 4 Gy+miR-873-5p group were higher than that in the 4 Gy+miR-NC group (2.35±0.16 vs. 1.84±0.14, 2.26±0.12 vs. 1.77±0.13; both P<0.05), but the expression of γH2AX protein in TPC-1 and KTC-1 cells of the 4 Gy+miR-873-5p+pcDNA-ANXA2 group were lower than that in the 4 Gy+miR-873-5p+pcDNA group (1.96±0.12 vs. 2.41±0.12, 1.92±0.07 vs. 2.28±0.12; both P<0.05). circ_0023990 targeted the negative regulation of miR-873-5p, and ANXA2 was the target gene of miR-873-5p. Conclusion: circ_0023990 was highly expressed in thyroid cancer tissues and cell lines, and it may promote the radiotherapy resistance of thyroid cancer cells in vivo through regulating miR-873-5p/ANXA2 axis.

Soluble (pro)renin receptor induces endothelial dysfunction and hypertension in mice with diet-induced obesity via activation of angiotensin II type 1 receptor

Until now, renin-angiotensin system (RAS) hyperactivity was largely thought to result from angiotensin II (Ang II)-dependent stimulation of the Ang II type 1 receptor (AT1R). Here we assessed the role of soluble (pro)renin receptor (sPRR), a product of site-1 protease-mediated cleavage of (pro)renin receptor (PRR), as a possible ligand of the AT1R in mediating: (i) endothelial cell dysfunction in vitro and (ii) arterial dysfunction in mice with diet-induced obesity. Primary human umbilical vein endothelial cells (HUVECs) treated with a recombinant histidine-tagged sPRR (sPRR-His) exhibited IκBα degradation concurrent with NF-κB p65 activation. These responses were secondary to sPRR-His evoked elevations in Nox4-derived H2O2 production that resulted in inflammation, apoptosis and reduced NO production. Each of these sPRR-His-evoked responses was attenuated by AT1R inhibition using Losartan (Los) but not ACE inhibition using captopril (Cap). Further mechanistic exploration revealed that sPRR-His activated AT1R downstream Gq signaling pathway. Immunoprecipitation coupled with autoradiography experiments and radioactive ligand competitive binding assays indicate sPRR directly interacts with AT1R via Lysine199 and Asparagine295. Important translational relevance was provided by findings from obese C57/BL6 mice that sPRR-His evoked endothelial dysfunction was sensitive to Los. Besides, sPRR-His elevated blood pressure in obese C57/BL6 mice, an effect that was reversed by concurrent treatment with Los but not Cap. Collectively, we provide solid evidence that the AT1R mediates the functions of sPRR during obesity-related hypertension. Inhibiting sPRR signaling should be considered further as a potential therapeutic intervention in the treatment and prevention of cardiovascular disorders involving elevated blood pressure.

Soluble (pro)renin receptor promotes the fibrotic response in renal proximal tubule epithelial cells in vitro via the Akt/β-catenin/Snail signaling pathway

Tubulointerstitial fibrosis has been regarded as a critical event in the pathogenesis of chronic kidney disease. The soluble form of (pro)renin receptor (sPRR), generated by site-1 protease (S1P) cleavage of full-length PRR, can be detected in biological fluid and elevated under certain pathological conditions. The present study was designed to evaluate the potential role of sPRR in the regulation of the fibrotic response in a cultured human renal proximal tubular cell line (HK-2 cells) in the setting of transforming growth factor (TGF)-β or sPRR-His treatment. The TGF-β-induced fibrotic response of HK-2 cells was indicated by upregulation of fibronectin (FN) expression; meanwhile, TGF-β could also induce the generation of sPRR, due to enhanced cleavage of full-length PRR. To explore the role of sPRR in the fibrotic response of HK-2 cells, we blocked the production of sPRR with a the S1P inhibitor PF429242 and found that PF429242 remarkably suppressed TGF-β-induced sPRR generation and FN expression in HK-2 cells. Administration of sPRR-His restored the PF429242-attenuated FN expression in HK-2 cells, indicating that sPRR could promote the TGF-β-induced fibrotic response. Furthermore, sPRR-His alone also increased the abundance of FN in HK-2 cells. These data suggested that sPRR was sufficient and necessary for the TGF-β-induced fibrotic response of HK-2 cells. Mechanistically, sPRR activated the AKT and β-catenin pathway in HK-2 cells, and blockade of the AKT or β-catenin pathway significantly abrogated sPRR-induced FN and Snail expression. Taking together, sPRR promoted the fibrotic response of HK-2 cells by activating Akt/β-catenin/Snail signaling, and it may serve as a potential therapeutic target in renal fibrosis.

Zero TE MRI for Craniofacial Bone Imaging

Zero TE MR imaging is a novel technique that achieves a near-zero time interval between radiofrequency excitation and data acquisition, enabling visualization of short-T2 materials such as cortical bone. Zero TE offers a promising radiation-free alternative to CT with rapid, high-resolution, silent, and artifact-resistant imaging, as well as the potential for "pseudoCT" reconstructions. In this report, we will discuss our preliminary experience with zero TE, including technical principles and a clinical case series demonstrating emerging applications in neuroradiology.

Mutation Analysis of Pre-mRNA Splicing Genes PRPF31, PRPF8, and SNRNP200 in Chinese Families with Autosomal Dominant Retinitis Pigmentosa

BACKGROUND

To screen variants in pre-mRNA Splicing genes in 95 Chinese autosomal dominant retinitis pigmentosa (adRP) families.

METHODS

Clinical examination and pedigree analysis were performed. Targeted exome sequencing (TES) and / or Sanger sequencing were performed to detect the variants in genes of Splicing factors and conduct intra-familiar segregation analysis with DNA available. In silico analysis was performed to predict pathogenicity of variants in protein level and in vitro splicing assays were performed to compare splicing variants with their corresponding wildtype about their splicing effect.

RESULTS

In this study, total nine different variants were identified in PRPF31, SNRNP200, and PRPF8 respectively, including six PRPF31 variants [five novel variants 322+1G>A, c.527+2T>G, c.590T>C(p.Leu197Pro), c.1035_1036insGC (p.Pro346Argfs X18), and c.1224dupG (p.Gln409AlafsX66) plus one reported variant c.1060C>T (p.Arg354X)], a recurrent PRPF8 variant c.6930G>T (p.Arg2310Ser), two SNRNP200 variants [one heterozygous and homozygous SNRNP200 recurrent variant c.3260G>A (p.Ser1087Leu), and a reported heterozygous c.2042G>A(p.Arg681His)]. In family 20009, incomplete penetrance was observed. A novel PRPF31 missense variant c.590T>C (p.Leu197Pro) was predicted to be pathogenic in protein level via in silico analysis and in vitro splicing assay demonstrated that two novel splicing PRPF31 variants c.322+1G>A and c.527+2T>G affect splicing compared with the wildtype.

CONCLUSIONS

In our studies, RP-causing variants of pre-mRNA Splicing genes (PRPF31, PRPF8 and SNRNP200) were identified in nine of the ninety-five adRP families respectively, which extend the spectra of RP variant and phenotype. And we provide the first example that SNRNP200-related RP can be caused by both heterozygous and homozygous variants of this gene.

Sodium butyrate attenuates angiotensin II-induced cardiac hypertrophy by inhibiting COX2/PGE2 pathway via a HDAC5/HDAC6-dependent mechanism

Sodium butyrate (NaBu) is reported to play important roles in a number of chronic diseases. The present work is aimed to investigate the effect of NaBu on angiotensin II (Ang II)-induced cardiac hypertrophy and the underlying mechanism in in vivo and in vitro models. Sprague Dawley rats were infused with vehicle or Ang II (200 ng/kg/min) and orally administrated with or without NaBu (1 g/kg/d) for two weeks. Cardiac hypertrophy parameters and COX2/PGE2 pathway were analysed by real-time PCR, ELISA, immunostaining and Western blot. The cardiomyocytes H9C2 cells were used as in vitro model to investigate the role of NaBu (2 mmol/L) in inhibition of Ang II-induced cardiac hypertrophy. NaBu significantly attenuated Ang II-induced increase in the mean arterial pressure. Ang II treatment remarkably increased cardiac hypertrophy as indicated by increased ratio of heart weight/body weight and enlarged cardiomyocyte size, extensive fibrosis and inflammation, as well as enhanced expression of hypertrophic markers, whereas hearts from NaBu-treated rats exhibited a significant reduction in these hypertrophic responses. Mechanistically, NaBu inhibited the expression of COX2/PGE2 along with production of ANP and phosphorylated ERK (pERK) stimulated by Ang II in in vivo and in vitro, which was accompanied by the suppression of HDAC5 and HDAC6 activities. Additionally, knocking down the expression of HDAC5 and HDAC6 via gene-editing strategy dramatically blocked Ang II-induced hypertrophic responses through COX2/PGE2 pathway. These results provide solid evidence that NaBu attenuates Ang II-induced cardiac hypertrophy by inhibiting the activation of COX2/PGE2 pathway in a HDAC5/HDAC6-dependent manner.

FPR2 enhances colorectal cancer progression by promoting EMT process

Formyl peptide receptor-2 (FPR2) has been shown to promote various tumors, but its role in colorectal cancer (CRC) has not been clearly illuminated. The aim of this study was to investigate the effect of FPR2 interference on cell proliferation, migration, invasion, apoptosis, pro-angiogenesis of CRC cells, and also the mechanisms involved. Quantitative PCR assays were applied to assess the expression levels of FPR2 in CRC tissues. CRC cell line SW1116 was chosen to perform this study. We knocked down FPR2 gene by sh-RNA. Then, the cell proliferation was assayed by soft agar colony formation assay, the cell migration capacity was checked by wound healing assay, and cell invasion ability was detected by transwell assay. In addition, flow cytometric analysis was used to detect apoptosis, while endothelial tube formation assay was used to evaluate the effects of FPR2 on pro-angiogenesis in vitro. Tumorigenesis experiment in vivo was performed in nude mice. EMT-related proteins were studied by western blotting. Quantitative PCR demonstrated that FPR2 mRNA was highly expressed in the colorectal cancer tissues. SW1116 cells' capacities of proliferation, migration, invasion, anti-apoptosis and pro-angiogenesis were distinctly suppressed after silencing FPR2 in SW1116 by sh-RNA. Suppression FPR2 mRNA in SW1116 cells suppressed tumorigenicity in nude mice. The expression of proteins related to epithelial-mesenchymal transition (EMT) such as E-cadherin, N-cadherin, Snail, Slug and vimentin was changed after suppressing FPR2. In conclusion, our study demonstrated that FPR2 could promote CRC cells progression in vitro and in vivo that may relate to promoting EMT.

(Pro)renin receptor contributes to pregnancy-induced sodium-water retention in rats via activation of intrarenal RAAS and α-ENaC

The (pro)renin receptor (PRR) is a new component of the renin-angiotensin-aldosterone system (RAAS) and regulates renin activity. The objective of the present study was to test potential roles of the renal PRR and intrarenal RAAS in the physiological status of late pregnancy. Late pregnant Sprague-Dawley rats were studied 19-21 days after sperm was observed in vaginal smears. Experiments were performed using age-matched virgin rats and late pregnant rats treated with the specific PRR inhibitor PRO20 (700 μg·kg-1·day-1 sc for 14 days, 3 times/day for every 8 h) or vehicle. The indices of RAAS, including PRR, renin, angiotensin II, and aldosterone levels, were examined by immunoblotting, qRT-PCR, or ELISA. Further analyses of renal epithelial sodium channel (ENaC) expression, sodium-water retention, and plasma volume were performed. We first present evidence for the activation of intrarenal RAAS in late pregnant rats, including increases in urinary renin activity, active and total renin content, and prorenin content, angiotensin II and aldosterone excretion, in parallel with increased renal PRR expression and urinary soluble PRR excretion. Functional evidence demonstrated that PRR antagonism with PRO20 effectively suppressed the indices of intrarenal RAAS in late pregnant rats. In addition, our results revealed that renal α-ENaC expression, sodium-water retention, and plasma volume were elevated during late pregnancy, which were all attenuated by PRO20. In summary, the present study examined the renal mechanism of sodium-water retention and plasma volume expansion in late pregnant rats and identified a novel role of PRR in regulation of intrarenal RAAS and α-ENaC and thus sodium and fluid retention associated with pregnancy.

miR-155 Aggravates Liver Ischemia/reperfusion Injury by Suppressing SOCS1 in Mice

Liver ischemia/reperfusion injury (IRI) occurs during partial liver resection and liver transplantation. Activation of Toll-like receptors (TLRs) is a key event triggered by a range of proinflammatory cytokines during liver I/R. Although it has been reported that miR-155 takes part in both innate and adaptive immune responses, the potential role of miR-155 in liver IRI remains unknown. In this study, we found that expression of miR-155 was upregulated during liver I/R by many inflammatory cytokines, and forced expression of miR-155 aggravated hepatocyte injury following liver I/R both in vivo and in vitro. Mice transfected with Ago-miR-155-a chemically modified miR-155-showed enhanced liver severity compared to those transfected with negative control miRNA by inhibiting the expression of SOCS1, the target of miR-155. Thus by the inhibition of SOCS1, the overexpression of miR-155 promoted activation of NF-κB, and elevating the production of proinflammatory cytokines, such TNF-α and IL-6. In conclusion, miR-155 aggravates liver I/R injury in vivo and hepatocyte hypoxia/reoxygenation injury by suppressing the expression of SOCS1.

FGF21 Prevents Angiotensin II-Induced Hypertension and Vascular Dysfunction by Activation of ACE2/Angiotensin-(1-7) Axis in Mice

Fibroblast growth factor 21 (FGF21) is a metabolic hormone with pleiotropic effects on glucose and lipid metabolism and insulin sensitivity. However, the role of FGF21 in hypertension remains elusive. Here we show that FGF21 deficiency significantly exacerbates angiotensin II-induced hypertension and vascular dysfunction, whereas such negative effects are reversed by replenishment of FGF21. Mechanistically, FGF21 acts on adipocytes and renal cells to promote induction of angiotensin-converting enzyme 2 (ACE2), which in turn converts angiotensin II to angiotensin-(1-7), then inhibits hypertension and reverses vascular damage. In addition, ACE2 deficiency strikingly abrogates these beneficial effects of FGF21 in mice, including alleviation of angiotensin II-associated hypertension and vascular damage. Otherwise, pharmaceutical inhibition of angiotensin-(1-7) attenuates the protective effect of FGF21 on angiotensin II-induced vascular dysfunction, but not on hypertension. Thus, FGF21 protects against angiotensin II-induced hypertension and vascular impairment by activation of the ACE2/angiotensin-(1-7) axis via fine-tuning the multi-organ crosstalk between liver, adipose tissue, kidney, and blood vessels.

Role of (pro)renin receptor in albumin overload-induced nephropathy in rats

Proteinuria is not only a common feature of chronic kidney diseases (CKD) but also an independent risk factor promoting CKD progression to end-stage renal failure. However, the underlying molecular mechanisms for protein overload-induced renal injury remain elusive. The present study examined the role of (pro)renin receptor (PRR) in pathogenesis of albumin overload (AO)-induced nephropathy and activation of the intrarenal renin-angiotensin system (RAS) in rats. Wistar rats underwent unilateral nephrectomy and were treated for 7 wk with vehicle, bovine serum albumin (5 g·kg^-1·day^-1 via a single ip injection), alone or in conjunction with the PRR decoy inhibitor PRO20 (500 μg·kg^-1·day^-1 via 3 sc injections). The AO rat model exhibited severe proteinuria, tubular necrosis, and interstitial fibrosis, oxidative stress, and inflammation, accompanied by elevated urinary N-acetyl-β-d-glucosaminidase activity and urinary β₂-microglobulin secretion, all of which were significantly attenuated by PRO20. Urinary and renal levels of renin, angiotensinogen, and ANG II were elevated by AO and suppressed by PRO20, contrasting to largely unaltered plasma levels of the RAS parameters. The AO model also showed increased renal expression of full-length PRR and soluble PRR (sPRR) and urinary excretion of sPRR. Taken together, we conclude that PRR antagonism with PRO20 alleviates AO-induced nephropathy via inhibition of intrarenal RAS.

NF-κB-dependent upregulation of (pro)renin receptor mediates high-NaCl-induced apoptosis in mouse inner medullary collecting duct cells

(Pro)renin receptor (PRR), a component of the renin-angiotensin system, has emerged as a new regulator of collecting duct function. The present study was designed to investigate the role of PRR in high salt-induced apoptosis in cultured mouse inner medullary collecting duct cells, mIMCD-K2 cells. Exposure to high NaCl at 550 mosM/kgH₂O increased PRR protein abundance, as did exposure to mannitol, sodium gluconate, or choline chloride. This was accompanied by upregulation of the abundance of phosphorylated NF-κB p65 protein. NF-κB inhibition with QNZ, caffeic acid phenethyl ester, or small interfering RNA (siRNA)-mediated silencing of NF-κB p65 attenuated high-NaCl-induced PRR upregulation. Exposure to high salt for 24 h induced apoptosis, as assessed by immunoblotting and immunocytochemistry analysis of cleaved caspase-3 and flow cytometry analysis of the number of apoptotic cells. High-NaCl-induced apoptosis was attenuated by a PRR decoy inhibitor, PRO20, or siRNA-mediated silencing of NF-κB p65. These results show that induction of PRR expression by exposure to high NaCl occurs through activation of NF-κB, thus contributing to cell apoptosis.

(Pro)renin receptor mediates albumin-induced cellular responses: role of site-1 protease-derived soluble (pro)renin receptor in renal epithelial cells

Proteinuria is a characteristic of chronic kidney disease and also a causative factor that promotes the disease progression, in part, via activation of the intrarenal renin-angiotensin system (RAS). (Pro)renin receptor (PRR), a newly discovered component of the RAS, binds renin and (pro)renin to promote angiotensin I generation. The present study was performed to test the role of soluble PRR (sPRR) in albumin overload-induced responses in cultured human renal proximal tubular cell line human kidney 2 (HK-2) cells. Bovine serum albmuin (BSA) treatment for 24 h at 20 mg/ml induced renin activity and inflammation, both of which were attenuated by a PRR decoy inhibitor PRO20. BSA treatment induced a more than fivefold increase in medium sPRR due to enhanced cleavage of PRR. Surprisingly, this cleavage event was unaffected by inhibition of furin or a disintegrin and metalloproteinase 19. Screening for a novel cleavage enzyme led to the identification of site-1 protease (S1P). Inhibition of S1P with PF-429242 or siRNA remarkably suppressed BSA-induced sPRR production, renin activity, and inflammatory response. Administration of a recombinant sPRR, termed sPRR-His, reversed the effects of S1P inhibition. In HK-2 cells overexpressing PRR, mutagenesis of the S1P, but not furin cleavage site, reduced sPRR levels. Together, these results suggest that PRR mediates albumin-induced cellular responses through S1P-derived sPRR.

Laparoscopic abdominoperineal excision with trans-abdominal individualized levator transection: interim analysis of a randomized controlled trial

AIM

Extralevator abdominoperineal excision (ELAPR) is challenging 'conventional' abdominoperineal excision (APR), yet the safety and efficacy of ELAPR is still under debate. We therefore developed a laparoscopic APR with trans-abdominal individualized levator transection (LAPR-TILT) approach and compared the outcome with a conventional laparoscopic APR (CLAPR).

METHOD

All eligible patients were entered a single-centre randomized controlled trial to compare CLAPR and LAPR-TILT. We assessed the first 185 patients, including operative findings, complications, histopathology and urogenital function.

RESULTS

Ninety-three patients in the CLAPR group and 92 patients in the APR-TILT group were included for analysis. The APR-TILT procedure took less time [137 (101-175) min vs 146 (102-187) min; P = 0.03], mainly owing to faster perineal dissection. APR-TILT resulted in a reduced rate of bowel perforation (1.1% vs 8.6%; P = 0.04), circumferential resection margin positivity (1.1% vs 10.8%; P = 0.01) and postoperative wound complications (5.4% vs 16.2%; P = 0.02) compared with the CLAPR procedure. At a median follow-up of 19 months after surgery, three patients (3.2%) in the CLAPR group had tumour recurrence while no tumour recurrence occurred in the LAPR-TILT group. Patients who underwent LAPR-TILT reported fewer urinary or sexual problems (LAPR-TILT vs CLAPR, 10.9% vs 24.7% and 17.4% vs 38.7%, respectively).

CONCLUSION

Compared with CLAPR, LAPR-TILT achieved better pathological results for factors that are surrogate parameters for local recurrence. LAPR-TILT could also reduce the risk of urogenital dysfunction.

Characterization of an entomopathogenic fungi target integument protein, Bombyx mori single domain von Willebrand factor type C, in the silkworm, Bombyx mori

The insect cuticle works as the first line of defence to protect insects from pathogenic infections and water evaporation. However, the old cuticle must be shed in order to enter the next developmental stage. During each ecdysis, moulting fluids are produced and secreted into the area among the old and new cuticles. In a previous study, the protein Bombyx mori single domain von Willebrand factor type C (BmSVWC; BGIBMGA011399) was identified in the moulting fluids of Bo. mori and demonstrated to regulate ecdysis. In this study we show that in Bo. mori larvae, BmSVWC primarily locates to the integument (epidermal cells and cuticle), wing discs and head. During the moulting stage, BmSVWC is released into the moulting fluids, and is then produced again by epidermal cells after ecdysis. Fungal infection was shown to decrease the amount of BmSVWC in the cuticle, which indicates that BmSVWC is a target protein of entomopathogenic fungi. Thus, BmSVWC is mainly involved in maintaining the integrity of the integument structure, which serves to protect insects from physical damage and pathogenic infection.

Activation of Renal (Pro)Renin Receptor Contributes to High Fructose-Induced Salt Sensitivity

A high-fructose diet is shown to induce salt-sensitive hypertension, but the underlying mechanism largely remains unknown. The major goal of the present study was to test the role of renal (pro)renin receptor (PRR) in this model. In Sprague-Dawley rats, high-fructose intake increased renal expression of full-length PRR, which were attenuated by allopurinol. High-fructose intake also upregulated renal mRNA and protein expression of sodium/hydrogen exchanger 3 and Na/K/2Cl cotransporter, as well as in vivo Na/K/2Cl cotransporter activity, all of which were nearly completely blocked by a PRR decoy inhibitor PRO20 or allopurinol treatment. Parallel changes were observed for indices of intrarenal renin-angiotensin-system including renal and urinary renin and angiotensin II levels. Radiotelemetry demonstrated that high-fructose or a high-salt diet alone did not affect mean arterial pressure, but the combination of the 2 maneuvers induced a ≈10-mm Hg increase of mean arterial pressure, which was blunted by PRO20 or allopurinol treatment. In cultured human kidney 2 cells, both fructose and uric acid increased protein expression of soluble PRR in a time- and dose-dependent manner; fructose-induced PRR upregulation was inhibited by allopurinol. Taken together, our data suggest that fructose via uric acid stimulates renal expression of PRR/soluble PRR that stimulate sodium/hydrogen exchanger 3 and Na/K/2Cl cotransporter expression and intrarenal renin-angiotensin system to induce salt-sensitive hypertension.

High potassium promotes mutual interaction between (pro)renin receptor and the local renin-angiotensin-aldosterone system in rat inner medullary collecting duct cells

(Pro)renin receptor (PRR) is predominantly expressed in the collecting duct (CD) with unclear functional implication. It is not known whether CD PRR is regulated by high potassium (HK). Here, we aimed to investigate the effect of HK on PRR expression and its role in regulation of aldosterone synthesis and release in the CD. In primary rat inner medullary CD cells, HK augmented PRR expression and soluble PPR (sPRR) release in a time- and dose-dependent manner, which was attenuated by PRR small interfering RNA (siRNA), eplerenone, and losartan. HK upregulated aldosterone release in parallel with an increase of CYP11B2 (cytochrome P-450, family 11, subfamily B, polypeptide 2) protein expression and upregulation of medium renin activity, both of which were attenuated by a PRR antagonist PRO20, PRR siRNA, eplerenone, and losartan. Similarly, prorenin upregulated aldosterone release and CYP11B2 expression, both of which were attenuated by PRR siRNA. Interestingly, a recombinant sPRR (sPRR-His) also stimulated aldosterone release and CYP11B2 expression. Taken together, we conclude that HK enhances a local renin-angiotensin-aldosterone system (RAAS), leading to increased PRR expression, which in turn amplifies the response of the RAAS, ultimately contributing to heightened aldosterone release.

Abstract P210: (Pro)Renin Receptor Regulates Potassium Homeostasis via Intrarenal Aldosterone

It has been shown that transgenic overexpression of human (pro)renin receptor (PRR) results in elevated aldosterone (Aldo) level with unclear functional implications. The present study examined a potential role of renal PRR during high K + (HK) loading. In normal SD rats, a 1-week HK intake (5% KCl in diet) induced a 3.4-fold increase in renal protein expression of full-length PRR and 4.2-fold increase in urinary excretion of soluble PRR (sPRR). Administration of PRO20, a decoy peptide antagonist of PRR, at 700 μg/kg/d via i.p. injections, to K + -loaded animals elevated plasma K + level (5.72+0.08 vs. 4.84±0.18 mM, p<0.05) and decreased urinary K + excretion (2.52+0.11 vs. 3.43+0.19 mmol/24h, p<0.05), accompanied with a 26.2% reduction of urinary aldosterone (Aldo) excretion. HK downregulated NCC protein expression (57.8%) and upregulated renal protein expression of aldosterone synthase CYP11B2 (229%), ROMK (156%), calcium-activated potassium channel subunit alpha-1 (α-BK) (367%), α-Na + -K + -ATPase (596%), and β-ENaC (155%), all of which were significantly blunted by PRO20 (by 50 - 70%). The same maneuvers were applied to adrenalectomized (ADX) rats. Although plasma Aldo was extremely low and also unresponsive to HK loading, urinary Aldo excretion was elevated by 274% with this treatment, which was abolished by PRO20. The HK-induced responses of the above K + and Na + transporting proteins in ADX rats all persisted and also remained sensitive to PRO20. Additionally, spironolactone treatment in ADX rats was still effective in inhibiting kaliuresis induced by HK loading, resulting in hyperkalemia (Plasma K+: 5.13±0.07 vs. 4.19±0.27 mM, p<0.05). In primary rat IMCD cells, exposure to 10 mM KCl for 24 h augmented PRR protein expression and sPRR release in a time- and dose-dependent manner. HK upregulated Aldo release in parallel with increased CYP11B2 protein expression, which were both attenuated by PRO20 or PRR siRNA. A recombinant sPRR, sPRR-His, stimulated Aldo release and CYP11B2 expression. Taken together, we conclude that HK increased renal PRR expression that stimulates renal synthesis of Aldo that coordinates the response of renal membrane Na + and K + transporting proteins to facilitate K + secretion.

Abstract P209: Activation of Renal (Pro)Renin Receptor Contributes to High Fuctose-induced Salt Sensitivity

A high-fructose (HF) diet is shown to induce salt-sensitive hypertension but the underlying mechanism remains unclear. The major goal of the present study was to test the role of renal (pro)renin receptor (PRR) in this model. Male Sprague-Dawley rats were randomly divided into the following 4 groups: 1) Control, 2) Fructose, 3) Fructose + PRO20, and 4) Fructose + allopurinol, and the treatments lasted for 3 months. Fructose was added to drinking water (as 20% solution) so was allopurinol (at 30 mg/kg/d). PRO20, an antagonist of (pro)renin receptor, was administered at 700 μg/kg/day via i.p. injections. High fructose (HF) intake induced a 150% increase in renal protein expression of full-length PRR (fPRR), which were attenuated by allopurinol. HF intake also upregulated renal mRNA and protein expression of NHE3 (206% for protein) and NKCC2 (169% for protein) as well as in vivo NKCC2 activity (2-fold increases in 1-h urine volume and UNaV), all of which were nearly completely blocked by PRO20 or allopurinol treatment. HF intake induced >5-fold increases in urinary renin activity, renin content, and total renin content, and a 2-fold increase in urinary AngII, which were suppressed by 60-70% with PRO20 or allopurinol, contrasting to relatively consistent values of these parameters in the plasma, evidence of involvement of intrarenal RAS . At the last week of the experimental period, radiotelemetry was performed to monitor blood pressure during one-week high salt (HS) diet (8% NaCl). The 3-mo HF intake or a 1-wk HS diet alone did not affect mean arterial pressure (MAP), but the combination of the two maneuvers induced a ~10 mm Hg increase of MAP, which was abolished by PRO20 or allopurinol treatment. In cultured human kidney 2 cells, both fructose and uric acid (UA) increased protein expression of soluble PRR (sPRR) in a time- and dose-dependent manner; fructose-induced PRR upregulation was inhibited by allopurinol. Taken together, our data suggest that fructose via UA stimulates renal expression of PRR/sPRR that stimulate NHE3 and NKCC2 expression and intrarenal RAS to induce salt-sensitive hypertension.

(Pro)Renin receptor regulates potassium homeostasis through a local mechanism

(Pro)renin receptor (PRR) is highly expressed in the distal nephron, but it has an unclear functional implication. The present study was conducted to explore a potential role of renal PRR during high K⁺ (HK) loading. In normal Sprague-Dawley rats, a 1-wk HK intake increased renal expression of full-length PRR and urinary excretion of soluble PRR (sPRR). Administration of PRO20, a decoy peptide antagonist of PRR, in K⁺-loaded animals elevated plasma K⁺ level and decreased urinary K⁺ excretion, accompanied with suppressed urinary aldosterone excretion and intrarenal aldosterone levels. HK downregulated Na⁺-Cl^- cotransporter (NCC) expression but upregulated CYP11B2 (cytochrome P-450, family 11, subfamily B, polypeptide 2), renal outer medullary K⁺ channel (ROMK), calcium-activated potassium channel subunit α₁ (α-BK), α-Na⁺-K⁺-ATPase (α-NKA), and epithelial Na⁺ channel subunit β (β-ENaC), all of which were blunted by PRO20. After HK loading was completed, urinary, but not plasma renin, was upregulated, which was blunted by PRO20. The same experiments that were performed using adrenalectomized (ADX) rats yielded similar results. Interestingly, spironolactone treatment in HK-loaded ADX rats attenuated kaliuresis but promoted natriuresis, which was associated with the suppressed responses of β-ENaC, α-NKA, ROMK, and α-BK protein expression. Taken together, we discovered a novel role of renal PRR in regulation of K⁺ homeostasis through a local mechanism involving intrarenal renin-angiotensin-aldosterone system and coordinated regulation of membrane Na⁺- and K⁺-transporting proteins.

Antidiuretic Action of Collecting Duct (Pro)Renin Receptor Downstream of Vasopressin and PGE2 Receptor EP4

Within the kidney, the (pro)renin receptor (PRR) is predominantly expressed in the collecting duct (CD), particularly in intercalated cells, and it is regulated by the PGE₂ receptor EP₄ Notably, EP₄ also controls urinary concentration through regulation of aquaporin 2 (AQP2). Here, we tested the hypothesis that sequential activation of EP₄ and PRR determines AQP2 expression in the CD, thus mediating the antidiuretic action of vasopressin (AVP). Water deprivation (WD) elevated renal PRR expression and urinary soluble PRR excretion in rats. Intrarenal infusion of a PRR decoy peptide, PRO20, or an EP₄ antagonist partially prevented the decrease in urine volume and the increase in urine osmolality and AQP2 expression induced by 48-hour WD. In primary cultures of rat inner medullary CD cells, AQP2 expression induced by AVP treatment for 24 hours depended on sequential activation of the EP₄ receptor and PRR. Additionally, mice lacking PRR in the CD exhibited increased urine volume and decreased urine osmolality under basal conditions and impaired urine concentrating capability accompanied by severe volume loss and a dangerous level of plasma hyperosmolality after WD. Together, these results suggest a previously undescribed linear AVP/PGE₂/EP₄/PRR pathway in the CD for regulation of AQP2 expression and urine concentrating capability.