"Every Cloud Has a Silver Lining": How Three Rare Diseases Defend Themselves from COVID-19 and What We Have Learnt from It.

The process of SARS-CoV-2 infection, responsible for the COVID-19 pandemic, is carried out through different steps, with the interaction between ACE2 and Spike protein (S) being crucial. Besides of that, the acidic environment of endosomes seems to play a relevant role in the virus uptake into cells and its intracellular replication. Patients affected by two rare genetic tubulopathies, Gitelman's and Bartter's Syndromes, and a rare genetic metabolic disease, Fabry Disease, have shown intrinsic protection from SARS-CoV-2 infection and COVID-19 on account of specific intrinsic features that interfere with the virus uptake into cells and its intracellular replication, which will be reported and discussed in this paper, providing interesting insights for present and future research.

The Ultrasound Renal Stress Test for the Assessment of Functional Renal Reserve in Kidney Transplantation: A Pilot Study in Living Donors.

In the evolving landscape of nephrology and kidney transplants, assessing renal functional reserve (RFR) in living kidney donors is essential for ensuring donor safety and successful transplantation. This study explores the use of the Intra-Parenchymal Renal Resistive Index Variation (IRRIV) test, a novel non-invasive method, to measure RFR in living donors. Our observational study included 11 participants undergoing living kidney donations, evaluated using the IRRIV-based Renal Stress Test (RST) before and 12 months post-nephrectomy. The study demonstrated significant changes in creatinine and eGFR CKD-EPI levels post-donation, with an average creatinine rise from 69 to 97 µmol/L and a reduction in eGFR from 104 to 66 mL/min/1.73 m2. These variations align with the expected halving of nephron mass post-nephrectomy and the consequent recruitment of RFR and hyperfiltration in the remaining nephrons. This pilot study suggests that the IRRIV-based RST is a practical, safe, and reproducible tool, potentially revolutionizing the assessment of RFR in living kidney donors, with implications for broader clinical practice in donor eligibility evaluation, even in borderline renal cases. Furthermore, it confirms the feasibility of RST in living kidney donors and allows us to assess the sample size in 48 donors for a future study.

EBV Reactivation in Transplant Recipients following SARS-CoV-2 Infection: A Retrospective Study.

Reactivation and primary infection with a high Epstein Barr Virus (EBV) DNA level in kidney transplant patients could cause severe complications, including the development of Post-Transplantation Lymphoproliferative Disease (PTLD). While in the general population the reactivation of EBV after SARS-CoV-2 infection has been reported, very few data are available in transplant recipients. Our retrospective study aimed to evaluate a possible EBV reactivation in kidney transplant patients following SARS-CoV-2 infection and a possible impairment of the immune system. In addition, the effects of changes in immunosuppressive therapy on EBV DNA reactivation and vaccination were also evaluated. A total of 166 kidney transplant patients followed at the Kidney-Pancreas Transplant Ambulatory Nephrology Unit at Padova University Hospital were retrospectively considered for an observation period of 6 months from January 2020 to April 2023. EBV DNA level was measured by Rt-PCR and evaluated 6 months before and after SARS-CoV-2 infection. Patients' serological states were established via quantification of anti-VCA and anti-EBNA (chemiluminescence). Patients' immune systems were characterized by CD4+/CD8+ lymphocyte ratio (flow cytometry). EBV DNA was reactivated in 50% of the 166 patients with COVID-19 who completed the study. Older patients with more severe forms of COVID-19 had higher EBV reactivation (p < 0.05). EBV reactivation significantly increased in patients with severe SARS-CoV-2 infection requiring hospitalization compared to patients managed at home (p < 0.001). CD4+/CD8+ lymphocyte ratio was reduced in patients with a younger age of transplant (p < 0.01) and on a higher dose of steroids (p < 0.01). The results of our study confirm the role of immunodepression, especially in recent transplant patients and those on high steroids, in EBV reactivation. These results combined with the few available in the literature might contribute to providing an optimal management of immunosuppressive treatment for these patients in order to obtain an immune state unfavorable to the activation of latent viruses, including EBV.

The RAAS Goodfellas in Cardiovascular System.

In the last two decades, the study of the renin-angiotensin-aldosterone system (RAAS) has revealed a counterregulatory protective axis. This protective arm is characterized by ACE2/Ang 1-7/MasR and Ang 1-9 that largely counteracts the classic arm of the RAAS mediated by ACE/Ang II/AT1R/aldosterone and plays an important role in the prevention of inflammation, oxidative stress, hypertension, and cardiovascular remodeling. A growing body of evidence suggests that enhancement of this counterregulatory arm of RAAS represents an important therapeutic approach to facing cardiovascular comorbidities. In this review, we provide an overview of the beneficial effects of ACE2, Ang 1-7/MasR, and Ang 1-9 in the context of oxidative stress, vascular dysfunction, and organ damage.

Varicella Zoster vaccination in hemodialysis patients: The state of the art.

Varicella Zoster Virus (VZV) infection is a common childhood exanthematous disease, which in adults and immunocompromised people may result in severe neurologic complications. Up to one-third of infected subjects may have VZV clinical reactivation particularly if immunocompromised. Patients affected by end-stage renal disease on hemodialysis present immunodepression that contributes to their higher incidence of VZV infections and reactivation. While antiviral treatment in these patients shows low efficacy, the prevention of VZV through vaccination avoids the primary infection and the risk of reactivation. Two VZV vaccines are currently available: the live attenuate Zoster Vaccine (LZV) and a Recombinant Zoster Vaccine (RZV), with the latter appearing to provide greater efficacy. Given the higher incidence of VZV infection and reactivation, the lesser response to antivirals and the lower impact of VZ vaccine in hemodialysis patients in terms of side effects, a higher diffusion of VZV vaccination should be promoted by nephrologists in these patients in particular in those with future transplant opportunities.

Safety of Citrate Anticoagulation in CKRT: Monocentric Experience of a Dynamic Protocol of Calcium Monitoring.

Regional Citrate Anticoagulation (RCA) is considered the first-line anticoagulation for Continuous Kidney Replacement Therapy (CKRT). The RCA requires strict protocols and trained staff to avoid unsafe use and ensure its benefit. We have analyzed all our CKRT prescriptions from December 2020 to April 2022 anonymously, collecting data on CKRT, lab tests, clinical conditions, and complications of RCA. In addition, in order to better detect citrate accumulation, we have performed an RCA protocol by reducing the CaTot/Ca2+ ratio cut-off from 2.50 to 2.40 and increasing the number of calcium checks according to its trend. Among the 374 patients in CKRT, 104 received RCA prescriptions, of which 11 (10.6%) were discontinued: 4 for the suspicion of citrate accumulation, 1 for the development of metabolic alkalosis, 1 for the shift to a different CKRT procedure due to the need for a higher bicarbonate dose, 4 for the elevation of hepatocytolysis indexes, and 1 due to a preemptive discontinuation following massive post-surgery bleeding. None of the patients have had citrate toxicity as indicated by a CaTot/Ca2+ greater than 2.50, and our protocol has allowed the early identification of patients who might develop clinical citrate toxicity.

Human parietal epithelial cells (PECs) and proteinuria in lupus nephritis: a role for ClC-5, megalin, and cubilin?

BACKGROUND: Parietal epithelial cells are a heterogeneous population of cells located on Bowman's capsule. These cells are known to internalize albumin with a still undetermined mechanism, although albumin has been shown to induce phenotypic changes in parietal epithelial cells. Proximal tubular cells are the main actors in albumin handling via the macromolecular complex composed by ClC-5, megalin, and cubilin. This study investigated the role of ClC-5, megalin, and cubilin in the parietal epithelial cells of kidney biopsies from proteinuric lupus nephritis patients and control subjects and identified phenotypical changes occurring in the pathological milieu. METHODS: Immunohistochemistry and immunofluorescence analyses for ClC-5, megalin, cubilin, ANXA3, podocalyxin, CD24, CD44, HSA, and LTA marker were performed on 23 kidney biopsies from patients with Lupus Nephritis and 9 control biopsies (obtained from nephrectomies for renal cancer). RESULTS: Two sub-populations of hypertrophic parietal epithelial cells ANXA3+/Podocalyxin-/CD44-, both expressing ClC-5, megalin, and cubilin and located at the tubular pole, were identified and characterized: the first one, CD24+/HSA-/LTA- had characteristics of human adult parietal epithelial multipotent progenitors, the second one, CD24-/LTA+/HSA+ committed to become phenotypically proximal tubular cells. The number of glomeruli presenting hypertrophic parietal epithelial cells positive for ClC-5, megalin, and cubilin were significantly higher in lupus nephritis patients than in controls. CONCLUSIONS: Our results may provide further insight into the role of hypertrophic parietal epithelial cells located at the tubular pole and their possible involvement in protein endocytosis in lupus nephritis patients. These data also suggest that the presence of hypertrophic parietal epithelial cells in Bowman's capsule represents a potential resource for responding to protein overload observed in other glomerulonephritis.

Oxidants and Cardiorenal Vascular Remodeling-Insights from Rare Genetic Tubulopathies: Bartter's and Gitelman's Syndromes.

Two human genetic tubulopathies, Bartter's (BS) and Gitelman's (GS) syndromes, have normo/hypotension and absent cardiac remodeling despite their apparent angiotensin system (RAS) activation. This seeming contradiction has led to an extensive investigation of BSGS patients, the result of which is that BSGS represents a mirror image of hypertension. BSGS's unique set of properties has then permitted their use as a human model to probe and characterize RAS system pathways and oxidative stress in cardiovascular and renal remodeling and pathophysiology. This review details the results using GSBS patients that provide a deeper understanding of Ang II signaling and its associated oxidants/oxidative stress in humans. By providing a more complete and complex picture of cardiovascular and renal remodeling pathways and processes, studies of GSBS can inform the identification and selection of new targets and therapies to treat these and other oxidant-related disorders.

Biochemical Mechanisms beyond Glycosphingolipid Accumulation in Fabry Disease: Might They Provide Additional Therapeutic Treatments?

Fabry disease is a rare X-linked disease characterized by deficient expression and activity of alpha-galactosidase A (α-GalA) with consequent lysosomal accumulation of glycosphingolipid in various organs. Currently, enzyme replacement therapy is the cornerstone of the treatment of all Fabry patients, although in the long-term it fails to completely halt the disease's progression. This suggests on one hand that the adverse outcomes cannot be justified only by the lysosomal accumulation of glycosphingolipids and on the other that additional therapies targeted at specific secondary mechanisms might contribute to halt the progression of cardiac, cerebrovascular, and renal disease that occur in Fabry patients. Several studies reported how secondary biochemical processes beyond Gb3 and lyso-Gb3 accumulation-such as oxidative stress, compromised energy metabolism, altered membrane lipid, disturbed cellular trafficking, and impaired autophagy-might exacerbate Fabry disease adverse outcomes. This review aims to summarize the current knowledge of these pathogenetic intracellular mechanisms in Fabry disease, which might suggest novel additional strategies for its treatment.

Calcineurin-Inhibitor-Induced Hypomagnesemia in Kidney Transplant Patients: A Monocentric Comparative Study between Sucrosomial Magnesium and Magnesium Pidolate Supplementation.

Magnesium (Mg) contributes to DNA stability, protein synthesis and cardiac excitability, while Mg deficiency leads to increased cardiovascular mortality, diabetes, hyperparathyroidism and risk of fractures. In kidney transplant patients, calcineurin inhibitors (CNIs) downregulating Mg channel TRPM6 in the distal collecting tubule induce early hypomagnesemia (HypoMg), which is associated with a faster decline in allograft function. A new formulation, sucrosomial Mg (SucrMg), for oral supplements encapsulates Mg oxide in a phospholipid membrane covered by a sucrester matrix, enhancing gastric and intestinal Mg absorption. This study has evaluated Mg bioavailability, effectiveness and tolerance of SucrMg compared to the conventional preparation of Mg pidolate (PidMg). The association of blood Mg with risk of post-transplant dysglycemia and hyperparathyroidism has also been investigated. Forty hypomagnesemic adult single, double or combined kidney-pancreas or kidney-liver transplant recipients within 2 years from transplantation were recruited. In total, 16 patients received PidMg and 27 received SucrMg. Blood Mg was measured at baseline (T0), after 15 days (T1) and after 6 months (T2) of treatment. PTH, fasting glucose and calcium were measured at baseline and after 6 months of treatment. The tolerance was evaluated at the ambulatory visits. SucrMg compared to PidMg was more efficient at increasing Mg bioavailability at T1: p < 0.0001 vs. p = 0.72 ns, respectively, with a ∆% increase of 12.4% vs. 5.4%, p = 0.04. Both preparations increased blood Mg at T2, p < 0.0001 and p = 0.002, respectively. SucrMg was better tolerated. No difference was observed for fasting plasma glucose, PTH and calcium. On one hand, our study is the first among transplant patients to evaluate the efficacy of SucrMg in the correction of HypoMg, which might justify the limited number of patients enrolled and the short observation time; on the other hand, our results could serve as a useful working hypothesis for further studies with a larger number of transplant patients and an extended study duration to confirm the benefits observed with SucrMg.

Slow Continuous Ultrafiltration in Regional Citrate Anticoagulation Performed with a Standard Fluid Infusion Central Venous Catheter in Intensive Care Unit for Fluid Overload in Acute on Chronic Heart Failure: A Case Report.

Slow continuous ultrafiltration (SCUF) is an extracorporeal therapy able to reduce fluid overload in chronic or acute heart failure resistant to diuretics. An in-vitro study demonstrated the SCUF feasibility using a standard fluid infusion central venous catheter (CVC). We describe the clinical application of this SCUF in regional citrate anticoagulation (SCUF-RCA) in a patient admitted to the Intensive Care Unit for acute decompensate heart failure with severe systemic fluid overload resistant to diuretics. To avoid risks deriving from a new catheterization, we used a pre-existing multi-lumen CVC for drug administration to provide 10 h of SCUF-RCA with a blood flow of 35 mL/min and 100 mL/h of ultrafiltration with a final weight loss of 1 Kilogram without technical and clinical complications. The patient had a hemodynamics improvement with the diuresis recovery from the previous oliguria after the SCUF-RCA. This clinical case can open the use of the SCUF-RCA in the clinical practice to treat the fluid overload unresponsive to maximal diuretic therapy not exposing the patient to the risks and complications related to the use of SCUF with CVC for dialysis and systemic anticoagulation with heparin. Accordingly, this technique may be useful in the treatment of fluid overload in outpatients.

Tracing angiotensin II's yin-yang effects on cardiovascular-renal pathophysiology.

Adverse changes in cardiovascular and renal systems are major contributors to overall morbidity and mortality. Human cardiovascular and renal systems exhibit a complex network of positive and negative feedback that is reflected in the control of vascular tone via angiotensin II (Ang II) based signaling. This review will examine in some depth, the multiple components and processes that control the status and reflect the health of these various cardiovascular and renal systems, such as pathways associated to monomeric G proteins, RhoA/Rho kinase system and ERK, oxidative stress and NO balance. It will specifically emphasize the "yin-yang" nature of Ang II signaling by comparing and contrasting the effects and activity of various systems, pathways and components found in hypertension to those found in Gitelman's and Bartter's syndromes (GS/BS), two rare autosomal recessive tubulopathies characterized by electrolytic imbalance, metabolic alkalosis, sodium wasting and prominent activation of the renin-angiotensin-aldosterone system. Notwithstanding the activation of the renin-angiotensin-aldosterone system, GS/BS are normo-hypotensive and protected from cardiovascular-renal remodeling and therefore can be considered the mirror image, the opposite of hypertension.

Conservative Management in End-Stage Kidney Disease between the Dialysis Myth and Neglected Evidence-Based Medicine.

In the last few decades, the aging of the general population has significantly increased the number of elderly patients with end-stage kidney disease (ESKD) who require renal replacement therapy. ESKD elders are often frail and highly comorbid with social issues and seem to not benefit from dialysis in terms of survival and quality of life. Conservative management (CM) could represent a valid treatment option, allowing them to live for months to years with a modest impact on their habits. Despite these possible advantages, CM remains underused due to the myth of dialysis as the only effective treatment option for all ESKD patients regardless of its impact on quality of life and survival. Both CM and dialysis remain valid alternatives in the management of ESKD. However, assessing comorbidities, disabilities, and social context should drive the choice of the best possible treatment for ESKD, while in elderly patients with short life expectancies, referring them to palliative care seems the most reasonable choice.

The Assessment of Renal Functional Reserve in ß-Thalassemia Major Patients by an Innovative Ultrasound and Doppler Technique: A Pilot Study.

Beta-thalassemia syndromes are the most common inherited monogenic disorders worldwide. The most common pathophysiologic and clinical renal disease manifestations of in ß-TM patients is the tubular dysfunctions related to iron overload, chronic anemia, and the need for chronic iron chelation therapy. The aim of this pilot study is to apply an innovative ultrasound and Doppler technique to assess the Renal Functional Reserve (RFR) in ß-TM patients, and to evaluate its reliability in iron overload tubulopathy. Ultrasound assessment of intra-parenchymal renal resistive index variation (IRRIV) has recently been proposed as a safe and reproducible technique to identify RFR presence. We define the preserved RFR when the Delta Renal Resistive Index (RRI) is >0.05 (baseline RRI­minimum RRI value during stress) in the Renal Stress Test (RST). Nineteen ß-TM patients were enrolled for this study. In our series, we found a strong negative correlation between mean ferritin values and Delta RRI (R = −0.51, p = 0.03). This pilot study suggested the RST as reliable tool for assessing the RFR by ultrasound. Specifically, RST could help in clinical practice suggesting the patient's management and iron chelation therapy.