SA-β-Gal in Kidney Tubules as a Predictor of Renal Outcome in Patients with Chronic Kidney Disease

Cellular senescence has emerged as an important driver of aging and age-related disease in the kidney. The activity of β-galactosidase at pH 6 (SA-β-Gal) is a classic maker of senescence in cellular biology; however, the predictive role of kidney tissue SA-β-Gal on eGFR loss in chronic kidney disease (CKD) is still not understood. We retrospectively studied the expression of SA-β-Gal in kidney biopsies obtained in a cohort [n = 22] of incident patients who were followed up for 3 years as standard of care. SA-β-Gal staining was approximately fourfold higher in the tubular compartment of patients with CKD vs. controls [26.0 ± 9 vs. 7.4 ± 6% positive tubuli in patients vs. controls; p < 0.025]. Tubular expressions of SA-β-Gal, but not proteinuria, at the time of biopsy correlated with eGFR loss at the follow up; moreover, SA-β-Gal expression in more than 30% of kidney tubules was associated with fast progressive kidney disease. In conclusion, our study shows that SA-β-Gal is upregulated in the kidney tubular compartment of adult patients affected by CKD and suggests that tubular SA-β-Gal is associated with accelerated loss of renal function.

Diagnosing Fabry nephropathy: the challenge of multiple kidney disease

Fabry disease (FD) is an X-linked inherited lysosomal disorder due to a deficiency of the enzyme alpha-galactosidase A (α-gla) due to mutations in the GLA gene. These mutations result in plasma and lysosome accumulation of glycosphingolipids, leading to progressive organ damage and reduced life expectancy. Due to the availability of specific disease-modifying treatments, proper and timely diagnosis and therapy are essential to prevent irreversible complications. However, diagnosis of FD is often delayed because of the wide clinical heterogeneity of the disease and multiple organ involvement developing in variable temporal sequences. This observation is also valid for renal involvement, which may manifest with non-specific signs, such as proteinuria and chronic kidney disease, which are also common in many other nephropathies. Moreover, an additional confounding factor is the possibility of the coexistence of FD with other kidney disorders. Thus, suspecting and diagnosing FD nephropathy in patients with signs of kidney disease may be challenging for the clinical nephrologist. Herein, also through the presentation of a unique case of co-occurrence of autosomal dominant polycystic kidney disease and FD, we review the available literature on cases of coexistence of FD and other renal diseases and discuss the implications of these conditions. Moreover, we highlight the clinical, laboratory, and histological elements that may suggest clinical suspicion and address a proper diagnosis of Fabry nephropathy.

The Contribution of Muscle Innate Immunity to Uremic Cachexia

Protein energy wasting (PEW) is a common complication both in chronic kidney disease (CKD) and end-stage kidney disease (ESKD). Of note, PEW is one of the stronger predictors of morbidity and mortality in this patient population. The pathogenesis of PEW involves several mechanisms, including anorexia, insulin resistance, acidosis and low-grade inflammation. In addition, "sterile" muscle inflammation contributes to PEW at an advanced CKD stage. Both immune and resident muscle cells can activate innate immunity; thus, they have critical roles in triggering "sterile" tissue inflammation. Toll-like receptor 4 (TLR4) can detect endogenous danger-associated molecular patterns generated or retained in blood in uremia and induce a sterile muscle inflammatory response via NF-κB in myocytes. In addition, TLR4, though the activation of the NLRP3 inflammasome, links the sensing of metabolic uremic stress in muscle to the activation of pro-inflammatory cascades, which lead to the production of IL-1β and IL-18. Finally, uremia-induced accelerated cell senescence is associated with a secretory phenotype that favors fibrosis in muscle. Targeting these innate immune pathways could lead to novel therapies for CKD-related PEW.

Combined extracorporeal CO2 removal and renal replacement therapy in a pregnant patient with COVID-19: a case report

Background. Pregnant women are at high risk of Coronavirus disease 2019 (COVID-19) complications, including acute respiratory distress syndrome. Currently, one of the cornerstones in the treatment of this condition is lung-protective ventilation (LPV) with low tidal volumes. However, the occurrence of hypercapnia may limit this ventilatory strategy. So, different extracorporeal CO2 removal (ECCO2R) procedures have been developed. ECCO2R comprises a variety of techniques, including low-flow and high-flow systems, that may be performed with dedicated devices or combined with continuous renal replacement therapy (CRRT). Case description. Here, we report a unique case of a pregnant patient affected by COVID-19 who required extracorporeal support for multiorgan failure. While on LPV, because of the concomitant hypercapnia and acute kidney injury, the patient was treated with an ECCO2R membrane inserted in series after a hemofilter in a CRRT platform. This combined treatment reducing hypercapnia allowed LPV maintenance at the same time while providing kidney replacement and ensuring maternal and fetal hemodynamic stability. Adverse effects consisted of minor bleeding episodes due to the anticoagulation required to maintain the extracorporeal circuit patency. The patient's pulmonary and kidney function progressively recovered, permitting the withdrawal of any extracorporeal treatment. At the 25th gestational week, the patient underwent spontaneous premature vaginal delivery because of placental abruption. She gave birth to an 800-gram female baby, who three days later died because of multiorgan failure related to extreme prematurity. Conclusions. This case supports using ECCO2R-CRRT combined treatment as a suitable approach in the management of complex conditions, such as pregnancy, even in the case of severe COVID-19.

MO582: Impaired HIF-1 Regulation in Skeletal Muscle of Patients With Advanced-Stage Chronic Kidney Disease

BACKGROUND AND AIMS

Tiredness and fatigue are common symptoms in patients with chronic kidney disease (CKD), but their underlying mechanisms are unknown and treatments unavailable. Patients with CKD display abnormalities along the entire oxygen cascade, with impaired diffusive and convective oxygen transport, thus contributing to a reduced tissue oxygen supply. Hypoxic adaptation is largely regulated by hypoxia-inducible factor 1 (HIF-1α), encoded by the HIF-1Α gene [1],  and peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α). In response to hypoxia or anemia, the muscle HIF-1α target genes increase oxygen transport through angiogenesis, responsiveness to insulin, cell proliferation and apoptosis/survival [2]. PGC-1α controls the expression of genes involved in mitochondrial biogenesis, energy homeostasis and glucose metabolism. PGC-1α is correlated with a total-body aerobic capacity [3], and its decrease has been detected in muscles of elderly persons and type 2 diabetes patients [3,4]. We hypothesized that desensitization of the HIF-1α driven oxygen-sensing mechanisms occurs in CKD patients.

METHOD

HIF-1α, PGC1α gene and protein expression, studied by Rt–PCR and immunohistochemistry, were assessed in the rectus abdominis muscle biopsies from 31 CKD patients with non-dialysis CKD 5 (18 M/13 F, eGFR 8 ± 1 mL/min) and were compared with those obtained in 10 subjects with normal renal function (7M/3F). 

HIF-1α,  PGC1α expression was studied also in C2C12 myotubes exposed to 10% normal serum or uremic serum (US) for 48 h. In addition, mitofusin-2 (MFN2), nuclear factor erythroid 2-related factor 2 (NRF2), and oxidative phosphorylation (OXPHOS) related to mitochondria integrity were monitored by Rt–PCR and/or western blot. Changes in the membrane potential were quantified by JC1 staining and fluorimeter analysis.

RESULTS

Despite anemia (Hb 9.5 ± 1 g/dL),  HIF-1α mRNA was severely blunted in the muscle of CKD patients, as well as PGC1α that resulted down-regulated in 62.5% of them (P &lt; 0.05) (Fig. 1). Log HIF-1α mRNA was directly related to log eGFR (r = 0.632, P &lt; 0.02), suggesting that the hypoxic response in muscle progressively down-regulates as the renal function declines. In cultured myotubes, US decreases PGC1α, HIF1α, MFN2, NRF2 and OXPHOS and membrane potential (P &lt; 0.05–0.01).

CONCLUSION

In patients with non-dialysis CKD, PGC1α and HIF1α are down-regulated, as well as in an in vitro model that resembles the uremic milieu. On the one hand, these findings are in keeping with impaired oxidative metabolism in the advanced stage of CKD, while on the other hand, they may account for the fatigue often referred by these patients. Moreover, our study suggests that the HIF prolyl hydroxylase inhibitor (HIF-PHIs), currently in clinical development, might be targeted on muscle metabolism and function and tested in the treatment of myopathy and fatigue in CKD.

FC027: Uric Acid Stimulates Cytoskeleton Pathways in Vascular Smooth Muscle Cells Through F-ACTIN Polymerization and Atrogin, Αsma and SM22 up Regulation

BACKGROUND AND AIMS

Hyperuricaemia (HU) has been identified as a risk factor for hypertension and renal disease. The most widely documented pathogenetic mechanisms for the uric acid (UA) mediated vascular and renal damage are vascular inflammation and remodeling.

 Vascular smooth muscle cells (VSMCs) possess a distinctive property of plasticity that allows the phenotypic transition and contributes to vascular remodeling. The aim of this study was to investigate UA effects on VSMC cell line, focusing on phenotypic transition and searching for possible signals involved in this process.

METHOD

MOVAS, a mouse VSMC cell line, was exposed for short (0–6 h) or long time (24–48 h) to 0 (No Treated cells: NT), 6, 9 and 12 mg/dL of UA, respectively. We evaluated cell viability by MTT test, migration property in a 48-well microchemotaxis chamber (using an 8 μm pore size, polycarbonate polyvinylpyrrolidone-free filters) and by phalloidin staining. Changes in cytoskeleton proteins [Smoothelin (SMT), alpha-Smooth Muscle Actin (αSMA), Smooth Muscle 22 Alpha (SM 22α)] were detected by real time polymerase chain reaction (rt-PCR) and Western blot. In addition, we evaluated angiotensin receptor 1 (AT1) and atrogin 1 expression by rt-PCR and Map kinase activation (Erk 1,2) by western blot. Lastly, we tested the UA effects on cellular changes through a prior treatment with angiotensin receptor blockers, Valsartan (V) and Losartan (L) 10 µmol.

RESULTS

A small increment in cell proliferation was observed at 24 h (+11%–15%; P &lt; 0.05). UA promoted an increased migratory rate in UA treated VSMCs at 24 and 48 h respect to untreated cells (P &lt; 0.001). These results were confirmed by F-actin intracellular distribution: the AlexaFluor 594-conjugate-phalloidin staining revealed a compact polymerization of F-actin in stress fibers along the major cell axis in untreated cells, while a re-arrangement in thinner and poorly oriented fibers localized at cortical level were found in UA treated cells (Fig. 1). When we evaluated cytoskeleton components, we found out that 24 h UA exposition rose up, SMT (2.5–3.4-fold; P &lt; 0.05), αSMA (1.3–1.5-fold; P &lt; 0.05) and SM 22α levels (1.3–2.5-fold P &lt; 0.05). Conversely, we found a 48 h UA treatment caused them to drop (SMT = –20%–40%, P &lt; 0.05; αSMA = –20%–40%, P &lt; 0.05; SM 22α = –30%–43%, P &lt; 0.05). Atrogin-1 was 2-fold up regulated at 48 h in UA treated VMSCs compared with NT (P = 0.04), suggesting a possible role for UA in cytoskeleton remodeling (Fig. 2). Furthermore, we observed a significant increase in VSMC area (+30%; P &lt; 0.001) regardless of UA concentration and time exposition. Supposing a key role of Angiotensin involvement in UA induced VSMCs changes, AT1 expression was assessed. We found AT1 was up regulated in UA treated VSMCs compared with NT (P = 0.04). As expected, V and L had inhibitory effects on AT1 upregulation. Moreover, the two angiotensin receptors blockers inhibited all the phenotypic changes induced by UA. Lastly, UA induced a time dependent Erk 1, 2 phosphorylation (1.5–2.5-fold versus T0; P &lt; 0.05–0.01), which was reversed by both L and V.

CONCLUSION

The results of this study show for the first time as UA-induced cytoskeletal changes involve polymerization of F-actin, Atrogin, αSMA and up-regulation of SM22.These results reveal the pathways by which UA induces an increase in VSMC area and in migratory rate, suggesting UA as a key player in vascular remodeling.

MO292: Clinical Characteristics, Management and Outcomes of Critically ill COVID-19 Patients Undergoing CRRT: Comparison Between the First Two Pandemic Waves

BACKGROUND AND AIMS

Acute kidney injury (AKI) is a common complication of coronavirus disease-19 (COVID-19), which, particularly in critically ill patients requiring continuous renal replacement therapy (CRRT), is associated with an elevated mortality risk [1, 2]. However, knowledge about COVID-19 pathogenesis and management is evolving, and clinical practice is changing rapidly. Here, we evaluated if this process had an impact on the management and outcome of AKI patients.

METHODS

We performed a retrospective observational study on critically ill adult COVID-19 patients who received CRRT in the intensive care unit (ICU) during the first two pandemic waves before the availability of COVID-19 vaccines: the first one from March to August 2020 (first) and the second one (second) from September to December 2020.

RESULTS

Overall, we considered 63 patients, aged 65 (60–69) years, 76.2% males. The main comorbidities were diabetes (DM), cardiovascular disease (CVD) and chronic kidney disease (CKD). Among them, 28 (44%) were in the first group and 35 (66%) in the second group. There were no significant differences in general characteristics, such as in comorbidities, except for a higher prevalence of CVD in the first group (Fig. 1). Lab examinations at ICU admission, including serum creatinine level (sCr), were not different between the two groups. While all patients required respiratory support, non-invasive ventilation was more prevalent in the second wave. Notably, during this period, decapneization combined with CRRT was introduced. Regarding drugs, we found that in the second group, hydroxychloroquine was abandoned, tocilizumab use was reduced and heparin administration significantly increased. The AKI time course was similar between the patients of the two waves (Fig. 2). There were no significant differences in CRRT techniques. However, in the second, the use of additional CRRT-devices, in particular adsorption-based filters, significantly increased. In most cases, citrate anticoagulation was used in both groups. Looking at the outcomes, we found no significant difference between the two waves. Indeed, 17 (60.2%) and 22 (62.8%) patients died in the ICU in the first and second groups, respectively. The length of ICU hospitalization, days on CRRT, invasive ventilation and DM were significantly related to overall mortality; time of ICU hospitalization was the only remaining significant at multivariate Cox regression. Overall, 21 (33%) patients survived hospitalization. At the 6 months after the discharge, 3 of them died, 3 were on HD and 15 were dialysis-free, even if 6 of them presented CKD.

CONCLUSION

Our data confirm the high complexity and mortality of COVID-19 patients undergoing CRRT. Comparing the first two pandemic waves, we found that the patients also presented similar characteristics in terms of renal function and AKI time course. Regarding treatments, we observed some significant modifications in the management of ventilation, drug administration and dialysis membranes, mainly because of the results of ongoing clinical trials. However, these changes did not impact patients’ outcomes.

These data support the view that only game-change strategies, such as vaccination or infection-specific drugs, may impact the presentation and outcome of COVID-19 patients undergoing CRRT.

Finally, patients surviving this condition deserve special attention in the follow-up.

DNMT3A epigenetically regulates key microRNAs involved in epithelial-to-mesenchymal transition in prostate cancer

Epithelial-to-Mesenchymal Transition (EMT) is involved in prostate cancer metastatic progression, and its plasticity suggests epigenetic implications. Deregulation of DNMTs and several miRNAs plays a relevant role in EMT, but their interplay has not been clarified yet. In this study we provide evidence that DNMT3A interaction with several miRNAs has a central role in an ex-vivo EMT prostate cancer model obtained via exposure of PC3 cells to conditioned media from cancer-associated fibroblasts (CM-CAFs). The analysis of the alterations of the miRNA profile shows that miR-200 family (miR-200a/200b/429, miR-200c/141), miR-205, and miR-203, known to modulate key EMT factors, are downregulated and hyper-methylated at their promoters. DNMT3A (mainly isoform a) is recruited onto these miRNA promoters, coupled with the increase of H3K27me3/H3K9me3 and/or the decrease of H3K4me3/H3K36me3. Most interestingly, our results reveal the differential expression of two DNMT3A isoforms (a and b) during ex-vivo EMT and a regulatory feedback loop between miR-429 and DNMT3A that can promote and sustain the transition toward a more mesenchymal phenotype. We demonstrate the ability of miR-429 to target DNMT3A 3'UTR and modulate the expression of EMT factors, in particular ZEB1. Survey of the PRAD-TCGA data set shows that patients expressing an EMT-like signature are indeed characterized by down-regulation of the same miRNAs with a diffused hyper-methylation at miR-200c/141 and miR-200a/200b/429 promoters. Finally, we show that miR-1260a also targets DNMT3A, although it does not seem involved in EMT in prostate cancer.

Artificial intelligence applied to non-contrast-enhanced cardiac computed tomography for the prediction of cardiovascular events

Background

Non-contrast-enhanced cardiac computed tomography (CT) may provide two measures that are emerging as independent predictors of cardiovascular events: coronary calcium score (CCS) and the volume of epicardial fat, a metabolically and immunologically active tissue surrounding the coronary arteries. The quantification of epicardial fat volume (EFV) is not routinely performed in clinical practice for the long time required for image reconstruction and the intra- and inter-observer variability.

Purpose

We evaluated if artificial intelligence (AI) might prove a valuable tool to interpret the CT data-set, and to better understand the relative prognostic value of CCS and EFV compared to “traditional” cardiovascular risk factors.

Methods

The Montignoso HEart and Lung Project is a community-based study carried out in a small town of Northern Tuscany (Italy). Starting from 2009, asymptomatic individuals from the general population underwent a baseline screening including a non-contrast cardiac CT, and were followed-up. For the present study, CCS and EFV were automatically measured from CT scans through a deep learning (DL) strategy based on convolutional neural networks. Because of the low incidence of the primary endpoint (myocardial infarction [MI]), the observed cardiac events were predicted with a random forest model built using a subsampling approach.

Results

Study participants (n=1528; 48% males, age 40 to 77 years) experienced 47 MI events (3%) over 5.5±1.5 years. CCS and EFV independently predicted this endpoint (p values &lt;0.001 and 0.005, respectively) in a model including other predictors, namely weight, age, male gender, and hypertension. The model displayed a good prognostic performance, with an out-of-bag accuracy of 80.43% (accuracy on non-event prediction: 81.17%; performance on event prediction: 57,45%). The CCS emerged as the most important predictor, followed by EFV, weight and age. Interestingly, the incidence of cardiovascular events linked with CCS levels was associated with elevated EFV and the subjects with elevated CCS values but low EFV had no events (figure 1).

Conclusions

The tools of AI allow to perform an automated analysis of non-contrast-enhanced CT scans, with rapid and accurate measurement of CCS and EFV through a DL approach. In asymptomatic individuals from the general population, these features are more predictive of non-fatal MI than other variables related to the cardiovascular risk, as we can be demonstrated through an application of AI.

Figure 1

Funding Acknowledgement

Type of funding source: None