Novel perspectives regarding the physiologic mechanisms by which gliflozins induce reticulocytosis and erythrocytosis.

Gliflozins provide a breakthrough in the management of type-2 diabetes. In addition to facilitating normoglycemia, these sodium-glucose cotransporter type 2 (SGLT2) inhibitors attenuate obesity, hypertension, dyslipidemia, and fluid retention, reduce cardiovascular morbidity, retard the progression of renal dysfunction, and improve survival. The administration of gliflozins also triggers erythropoietin (EPO) production, with the consequent induction of reticulocytosis and erythrocytosis. The mechanism(s) by which gliflozins induce erythropoiesis is a matter of debate. Whereas the canonical pathway of triggering EPO synthesis is through renal tissue hypoxia, it has been suggested that improved renal oxygenation may facilitate EPO synthesis via noncanonical trails. The latter proposes that recovery of peritubular interstitial fibroblasts producing erythropoietin (EPO) is responsible for enhanced erythropoiesis. According to this hypothesis, enhanced glucose/sodium reuptake by proximal tubules in uncontrolled diabetes generates cortical hypoxia, with injury to these cells. Once transport workload declines with the use of SGLT2i, they recover and regain their capacity to produce EPO. In this short communication, we argue that this hypothesis is incorrect. First, there is no evidence for interstitial cell injury related to hypoxia in the diabetic kidney. Tubular, rather than interstitial cells are prone to hypoxic injury in the diabetic kidney. Moreover, hypoxia, not normoxia, stimulates EPO synthesis by hypoxia-inducible factors (HIFs). Hypoxia regulates EPO synthesis as it blocks HIF prolyl hydroxylases (that initiate HIF alpha degradation), hence stabilizing HIF signals, inducing HIF-dependent genes, including EPO located in the deep cortex, and its production is initiated by the apocrinic formation of HIF-2, colocalized in these same cells.

An Innovative Ultrasound Technique for Early Detection of Kidney Dysfunction: Superb Microvascular Imaging as a Reference Standard.

BACKGROUND: Superb microvascular imaging (SMI) is an innovative ultrasound image processing technique that provides greater detail and better visualization of small branching vessels. We assume that SMI will provide sufficient information regarding the severity of chronic kidney disease (CKD) and reflecting histological changes. AIMS: The aims was to assess the capabilities of SMI imaging regarding the early detection of kidney dysfunction and renal fibrosis in comparison to the reference standard renal biopsy for the early diagnosis of kidney fibrosis. METHODS: SMI was performed in patients (n = 52) with CKD stage 2-5, where some of them underwent biopsy proven CKD and fibrosis as part of the diagnosis. In addition, biochemical tests were performed, including kidney function tests, urine collection for proteinuria, and the estimation of GFR by MDRD or CKD-EPI eGFR in CKD patients and healthy controls (n = 17). All subjects underwent SMI, where vascularity is expressed as the SMI index (a low index reflects low vascularity/fibrosis and vice versa). RESULTS: The SMI vascular index was significantly lower in CKD patients as compared with healthy controls (72.2 ± 12.9 vs. 49.9 ± 16.7%, p < 0.01). Notably, a moderate correlation between the SMI index and eGFR was found among the CKD patients (r = 0.56, p < 0.001). Similarly, a strong correlation was found between SCr and the SMI index of the diseased subjects (r = -0.54, p < 0.001). In patients who underwent renal biopsy, the SMI index corresponded with the histological alterations and CKD staging. CONCLUSIONS: This study demonstrated that SMI imaging may be utilized in CKD patients of various stages for the evaluation of chronic renal morphological changes and for differentiation between CKD grades.

Renal Manifestations of Covid-19: Physiology and Pathophysiology.

Corona virus disease 2019 (COVID-19) imposes a serious public health pandemic affecting the whole world, as it is spreading exponentially. Besides its high infectivity, SARS-CoV-2 causes multiple serious derangements, where the most prominent is severe acute respiratory syndrome as well as multiple organ dysfunction including heart and kidney injury. While the deleterious impact of SARS-CoV-2 on pulmonary and cardiac systems have attracted remarkable attention, the adverse effects of this virus on the renal system is still underestimated. Kidney susceptibility to SARS-CoV-2 infection is determined by the presence of angiotensin-converting enzyme 2 (ACE2) receptor which is used as port of the viral entry into targeted cells, tissue tropism, pathogenicity and subsequent viral replication. The SARS-CoV-2 cellular entry receptor, ACE2, is widely expressed in proximal epithelial cells, vascular endothelial and smooth muscle cells and podocytes, where it supports kidney integrity and function via the enzymatic production of Angiotensin 1-7 (Ang 1-7), which exerts vasodilatory, anti-inflammatory, antifibrotic and diuretic/natriuretic actions via activation of the Mas receptor axis. Loss of this activity constitutes the potential basis for the renal damage that occurs in COVID-19 patients. Indeed, several studies in a small sample of COVID-19 patients revealed relatively high incidence of acute kidney injury (AKI) among them. Although SARS-CoV-1 -induced AKI was attributed to multiorgan failure and cytokine release syndrome, as the virus was not detectable in the renal tissue of infected patients, SARS-CoV-2 antigens were detected in kidney tubules, suggesting that SARS-CoV-2 infects the human kidney directly, and eventually induces AKI characterized with high morbidity and mortality. The mechanisms underlying this phenomenon are largely unknown. However, the fact that ACE2 plays a crucial role against renal injury, the deprivation of the kidney of this advantageous enzyme, along with local viral replication, probably plays a central role. The current review focuses on the critical role of ACE2 in renal physiology, its involvement in the development of kidney injury during SARS-CoV-2 infection, renal manifestations and therapeutic options. The latter includes exogenous administration of Ang (1-7) as an appealing option, given the high incidence of AKI in this ACE2-depleted disorder, and the benefits of ACE2/Ang1-7 including vasodilation, diuresis, natriuresis, attenuation of inflammation, oxidative stress, cell proliferation, apoptosis and coagulation.

Waning Humoral Response 3 to 6 Months after Vaccination with the SARS-COV-2 BNT162b2 mRNA Vaccine in Dialysis Patients.

BACKGROUND AND OBJECTIVES: The short-term reported antibody response to SARS-COV-2 vaccination in dialysis patients is high, with a seroconversion response rate up to 97%. Data on the long-term durability of this response are scarce. Our objective was to characterize the long-term anti-spike antibody level in dialysis patients. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: In an observational study, we measured SARS-COV-2 anti-spike antibody levels in dialysis patients who completed 2 doses of the BNT162b2 mRNA SAR S-COV-2 vaccine at 1, 3 and 6 months after the second vaccine dose. We compared the response to dialysis patients who were infected with COVD-19 and to a control group of healthcare-employees. RESULTS: One hundred and forty-two dialysis patients who had been vaccinated (ages 64 ± 11.9 years, 61% male), 33 dialysis patients who had COVID-19 infection (ages 54 ± 14.3 years, 55% male) and 104 individuals in the control group (ages 50 ± 12.2 years, 44% male) were included. The response rate in the vaccinated dialysis patients was 94%, 78% and 73% at 1, 3 and 6 months after the second vaccine dose. In the COVID-19 infected dialysis group and in the control group, the response rate remained at 100% over 6 months. The percentage of change in antibody levels between one and 6 months was -66% in the vaccinated dialysis group, -28% in the control group (p < 0.001) and +48% in dialysis patients who had been infected with COVID-19 (p < 0.001). A non-responder status at 6 months was associated with a lower albumin level. No serious adverse events following vaccination were reported. In conclusion: the initially high response rate to the BNT162b2 vaccine in dialysis patients decreases rapidly. Our results indicate that an early booster (3rd) dose, at three months after the second dose, may be advised for this population to preserve the humoral immunity.

ACE2, COVID-19 Infection, Inflammation, and Coagulopathy: Missing Pieces in the Puzzle.

Engulfed by the grave consequences of the coronavirus disease 2019 (COVID-19) pandemic, a better understanding of the unique pattern of viral invasion and virulence is of utmost importance. Angiotensin (Ang)-converting enzyme (ACE) 2 is a key component in COVID-19 infection. Expressed on cell membranes in target pulmonary and intestinal host cells, ACE2 serves as an anchor for initial viral homing, binding to COVID-19 spike-protein domains to enable viral entry into cells and subsequent replication. Viral attachment is facilitated by a multiplicity of membranal and circulating proteases that further uncover attachment loci. Inherent or acquired enhancement of membrane ACE2 expression, likely leads to a higher degree of infection and may explain the predisposition to severe disease among males, diabetics, or patients with respiratory or cardiac diseases. Additionally, once attached, viral intracellular translocation and replication leads to depletion of membranal ACE2 through degradation and shedding. ACE2 generates Ang 1-7, which serves a critical role in counterbalancing the vasoconstrictive, pro-inflammatory, and pro-coagulant effects of ACE-induced Ang II. Therefore, Ang 1-7 may decline in tissues infected by COVID-19, leading to unopposed deleterious outcomes of Ang II. This likely leads to microcirculatory derangement with endothelial damage, profound inflammation, and coagulopathy that characterize the more severe clinical manifestations of COVID-19 infection. Our understanding of COVID-ACE2 associations is incomplete, and some conceptual formulations are currently speculative, leading to controversies over issues such as the usage of ACE inhibitors or Ang-receptor blockers (ARBs). This highlights the importance of focusing on ACE2 physiology in the evaluation and management of COVID-19 disease.

Haptoglobin phenotype among patients with IgA nephropathy: Impact on disease progression and response to treatment.

BACKGROUND: IgA nephropathy (IgAN) is characterized by proteinuria, hypertension, and decreased glomerular filtration rate at the time of diagnosis. However, the underlying mechanism is still obscure. The impact of haptoglobin (Hp) phenotype, as a genetic risk factor, on the progression of IgAN has not been studied yet. The current study examines whether Hp phenotype influences IgAN progression and response to treatment. MATERIALS AND METHODS: The study included 40 patients with IgAN, 26 non-IgAN chronic kidney disease (CKD), 114 patients on hemodialysis, and 150 healthy subjects. Blood and urine samples were collected at baseline and 6 months after initiation therapy. Serum creatinine, total proteinuria, and Hp phenotype were determined in all patients and healthy controls. RESULTS: Approximately 17% of IgAN patients were Hp 1-1, 40% Hp 2-1, and 42.5% Hp 2-2. In contrast, in non-IgAN CKD patients, the prevalence of Hp 1-1, Hp 2-1, and Hp 2-2 was 8%, 19%, and 73%, respectively. In hemodialytic patients, prevalence of Hp 1-1, Hp 2-1, and Hp 2-2 was 10.5, 49.1, and 40.4%, respectively. In healthy subjects, the distribution of Hp 1-1, Hp 2-1, and Hp 2-2 was 7, 39, and 54%, respectively. Interestingly, IgAN Hp 2-2 and Hp 2-1 patients were more stable and responded better to treatment with routine therapy than other patients with Hp phenotype. CONCLUSION: The prevalence of Hp 1-1 phenotype is higher in IgAN patients than in the general population in Israel, and even more than in patients with CKD or subjects on hemodialysis. Patients with Hp 2-2 exhibited a better renal response to the routine therapies.

Glycocalyx Degradation in Ischemia-Reperfusion Injury.

The glycocalyx is a layer coating the luminal surface of vascular endothelial cells. It is vital for endothelial function as it participates in microvascular reactivity, endothelium interaction with blood constituents, and vascular permeability. Structural and functional damage to glycocalyx occurs in various disease states. A prominent clinical situation characterized by glycocalyx derangement is ischemia-reperfusion (I/R) of the whole body as well as during selective I/R to organs such as the kidney, heart, lung, or liver. Degradation of the glycocalyx is now considered a cornerstone in I/R-related endothelial dysfunction, which further impairs local microcirculation with a feed-forward loop of organ damage, due to vasoconstriction, leukocyte adherence, and activation of the immune response. Glycocalyx damage during I/R is evidenced by rising plasma levels of its principal constituents, heparan sulfate and syndecan-1. By contrast, the concentrations of these compounds in the circulation decrease after successful protective interventions in I/R, suggesting their use as surrogate biomarkers of endothelial integrity. In light of the importance of the glycocalyx in preserving endothelial cell integrity and its involvement in pathologic conditions, several promising therapeutic strategies to restore the damaged glycocalyx and to attenuate its deleterious consequences have been suggested. This review focuses on alterations of glycocalyx during I/R injury in general (to vital organs in particular), and on maneuvers aimed at glycocalyx recovery during I/R injury.

Impact of pretreatment with carnitine and tadalafil on contrast-induced nephropathy in CKD patients.

Objective: The present study assesses whether phosphodiesterase type 5 (PDE-5) inhibitor or carnitine exert nephroprotective effects against clinical contrast-induced nephropathy (CIN).Materials and Methods: The present study consisted of three groups of CKD patients. The first group was control group, who were treated with N-acetyl-L-cysteine 1 day before and on the day of radiocontrast administration. The second one was carnitine group, where the patients were infused with carnitine over 10 min 2 h prior to the radiocontrast administration and 24 h post CT. The third one was PDE-5 inhibitor group, where patients were given tadalafil 2 h prior to the administration of the radiocontrast and in the subsequent day. Urine and blood samples were collected before and at the following time sequence: 2, 6, 12, 24, 48, and 120 h after the contrast administration, for creatinine and NGAL determination.Results: Pretreated with N-acetyl-L-cysteine prior to administration of contrast media (CM) to CKD patients caused a significant increase in urinary but not of plasma neutrophil gelatinase-associated lipocalin (NGAL) and serum creatinine (SCr). In contrast, pretreatment with carnitine prevented the increase in urinary NGAL and reduced SCr below basal levels. Similarly, tadalafil administration diminished the elevation of CM-induced urinary NGAL.Conclusions: These results indicate that carnitine and PDE-5 inhibitors may comprise potential therapeutic maneuvers for CIN.

[PREECLAMPSIA: PATHOGENESIS AND MECHANISMS BASED THERAPEUTIC APPROACHES].

INTRODUCTION: Preeclampsia is a serious complication of pregnancy affecting 3-8% of all pregnancies. It increases the morbidity and mortality of both the fetus and the pregnant woman, especially in developing countries. It deleteriously affects several vital organs, including the kidney, heart, liver, brain, and lung. Although, the pathogenesis of preeclampsia has not yet been fully understood, growing evidence suggests that aberrations in the angiogenic factors levels/activity and coagulopathy are responsible for the clinical manifestations of the disease. The common nominator of tissue damage of all these target organs is endothelial injury, which impedes their normal function. At the renal level, glomerular endothelial injury leads to the development of maternal hypertension and proteinuria. Similarly, this disease can cause hepatic and neurologic dysfunction due to vascular damage. The current review summarizes the recent development in the pathogenesis of this disease state with special focus on novel diagnostic biomarkers and their relevance to potential therapeutic options for preeclampsia. Specifically, we will highlight the renal manifestations of the diseases with emphasis on the involvement of angiogenic factors in vascular injury and how restoration of the angiogenic balance affects the renal and cardiovascular outcome of preeclamptic women.

Tumor Lysis Syndrome in Chronic Lymphocytic Leukemia: A Rare Case Report from Nephrology.

BACKGROUND Tumor lysis syndrome is common in hematological malignancy, but less frequent in chronic and solid tumors. Almost always it is observed after chemotherapy or radiotherapy initiation, but rarely occurs spontaneously. CASE REPORT A 89-year-old female with stable chronic lymphocytic leukemia was admitted to the hospital because of worsening dyspnea and dry cough. Her vital signs were normal, except for sinus tachycardia. On physical examination, she appeared distressed, dyspneic, sweaty but afebrile, anxious, but alert and well oriented. Lung examination revealed reduced air entry with bibasilar crackles. No peripheral edema was seen, pulses were normal, and no signs of deep vein thrombosis were observed. Laboratory analysis revealed leukocytosis; but normal hematological and biochemical parameters. Intravenous (IV) furosemide and antibiotics (IV ceftriaxone and orally azithromycin) were started along with steroid therapy (methylprednisolone 62.5 mg, IV). The treatment with steroids lasted for 1 day only, and in the following day, the patient was switched to prednisone (20 mg/day orally) for only 1 additional day. White blood cell count increased on day 1, 2 and 3 after admission, along development of hyperuricemia, hyperphosphatemia, hyperkalemia, acute renal failure and elevated troponin levels. Hemodiafiltration/hemodialysis was initiated, and the patient was discharged after serum concentrations of these electrolytes and kidney function were restored. One month after discharge, the patient denied any malaise and was at stable condition. CONCLUSIONS Herein, we present a case of a patient with stable chronic lymphocytic leukemia, who developed spontaneous tumor lysis syndrome after short low dose of steroid therapy. This case highlights the importance of including spontaneous tumor lysis syndrome in the differential diagnosis of any acute renal failure in the constellation of any malignancy.

Preeclampsia: Novel Mechanisms and Potential Therapeutic Approaches.

Preeclampsia is a serious complication of pregnancy where it affects 5-8% of all pregnancies. It increases the morbidity and mortality of both the fetus and pregnant woman, especially in developing countries. It deleteriously affects several vital organs, including the kidneys, liver, brain, and lung. Although, the pathogenesis of preeclampsia has not yet been fully understood, growing evidence suggests that aberrations in the angiogenic factors levels and coagulopathy are responsible for the clinical manifestations of the disease. The common nominator of tissue damage of all these target organs is endothelial injury, which impedes their normal function. At the renal level, glomerular endothelial injury leads to the development of maternal proteinuria. Actually, peripheral vasoconstriction secondary to maternal systemic inflammation and endothelial cell activation is sufficient for the development of preeclampsia-induced hypertension. Similarly, preeclampsia can cause hepatic and neurologic dysfunction due to vascular damage and/or hypertension. Obviously, preeclampsia adversely affects various organs, however it is not yet clear whether pre-eclampsia per se adversely affects various organs or whether it exposes underlying genetic predispositions to cardiovascular disease that manifest in later life. The current review summarizes recent development in the pathogenesis of preeclampsia with special focus on novel diagnostic biomarkers and their relevance to potential therapeutic options for this disease state. Specifically, the review highlights the renal manifestations of the disease with emphasis on the involvement of angiogenic factors in vascular injury and on how restoration of the angiogenic balance affects renal and cardiovascular outcome of Preeclamptic women.

Elevated Neutrophil Gelatinase Lipocalin Levels Are Associated With Increased Oxidative Stress in Hemodialysis Patients.

BACKGROUND: Administration of intravenous iron is an essential treatment of anemia in hemodialysis patients, but it may lead to oxidative stress and increased morbidity and mortality. There is evidence that neutrophil gelatinase-associated lipocalin (NGAL) is protective against oxidative stress and thus the aim of the present study was to investigate the relationship between plasma NGAL and advanced oxidative protein products (AOPP) in hemodialysis patients treated with intravenous iron. METHODS: In a prospective study, 47 hemodialysis patients (mean age 63 years, SD = 13.6; 40% women) were enrolled from two separate hospitals. Oxidative stress was induced by an intravenous administration of 100 mg iron saccharate 0.5 h after the start of dialysis. Blood samples were drawn at the beginning of the dialysis, 0.5 h after iron administration and at the end of dialysis. NGAL levels were measured from the first blood sample, AOPP levels were measured from all blood samples. RESULTS: Our results showed that higher NGAL and AOPP levels at the beginning of the dialysis, prior to iron administration, significantly predicted higher levels of AOPP toward the end of dialysis, (ß = 0.355, SE = 0.054, P = 0.035; ß = 0.297, SE = 0.159, P = 0.043, respectively). CONCLUSIONS: Our results suggest that higher level of NGAL is a risk factor for oxidative stress, as measured by AOPP levels, in dialysis patients receiving intravenous iron. Our findings could identify dialysis patients who are at higher risk from iron supplementation via measurement of NGAL levels.

Haptoglobin Phenotype Among Arab Patients With Mental Disorders.

BACKGROUND: Depression, schizophrenia and panic disorder are common mental disorders in the community and hospitalized patients. These mental disorders negatively affect life quality and even expectancy of life. Haptoglobin (Hp) phenotype (Hp 1-1, 1-2, or 2-2) is associated with risk for cardiovascular diseases, but its association with psychiatric disorders, a growing concern in the modern society, has not been studied thoroughly. The aim of the study was to examine whether Hp phenotype is associated with common mental disorders such as depression, schizophrenia, and panic disorder. METHODS: The study included 92 Arab patients with mental disorders, and among them 44 suffered from schizophrenia (mean age 39 ± 1.5 years), 17 from depression (mean age 44.5 ± 3.1 years), 31 from panic disorder (mean age of 44.9 ± 2.7 years), and 206 healthy Arab control subjects with a mean age of 42.6 ± 0.9 years. Beck's depression inventory assessment and Hamilton depression scale were administered for depression and panic disorder diagnosis. Schizophrenia was evaluated with positive and negative affect schedule (Panas) test. All mental disorders were evaluated by clinical review. Blood analysis for Hp phenotype was performed. Diagnosis was made using the Diagnostic and Statistical Manual of Mental Disorders axis to correlate depression with Hp phenotype. RESULTS: In mentally healthy controls, 10.7% were Hp 1-1, 38.8% Hp 2-1, and 50.5% Hp 2-2. In patients with the studied psychiatric disorders, Hp phenotype was comparable to healthy subjects; 8.7% were Hp 1-1, 50% Hp 2-1, and 41.3% Hp 2-2. When Hp phenotyping was analyzed in the psychiatric subgroups, Hp 2-1 was more common among depressed and schizophrenic patients, as compared with healthy subjects (58.8% and 52.3% vs. 38.8%). In patients who suffer from panic disorder, Hp phenotype distribution was 6.5% Hp 1-1, 41.9% Hp 2-1, and 51.6% Hp 2-2, suggesting a lower prevalence among Hp 1-1 phenotype. CONCLUSIONS: Arab patients who carry Hp 2-1 phenotype may be at risk to develop depression or schizophrenia more than the general healthy population. In contrast, Hp 1-1 subjects have a lower prevalence of panic disorder.

Superb Microvascular Imaging: Added Value and Novel Applications.

Determining the presence and characteristics of vascular flow is an essential part of sonography interrogation. However, small vessels and low velocities are not always possible to depict with conventional color and power Doppler ultrasound. This can be frustrating, especially when the diagnosis depends mainly on the existence of vascular flow, the sonographic examination will be inconclusive, further imaging examinations will be required and diagnosis delayed. Superb microvascular imaging (SMI) is a novel vascular imaging mode, which provides visualization of low velocity and microvascular flow. SMI uses a clutter suppression algorithm to extract flow signals and depicts this information as a color overlay image or as a monochrome or color map of flow. By using SMI, high frame rates and high-resolution images remain maintained. With SMI, it is possible to visualize small vessels including their branches that, until now, it is possible to demonstrate only using contrast-enhanced ultrasound. Availability of this additional technology on all ultrasound machines may make some of the computed tomography scans unnecessary. In our paper, we describe six patients, aged 16-73 years, in which final diagnosis was achieved only with SMI and where conventional color and power Doppler failed. All these examinations were performed using Aplio 500 Platinum ultrasound unit (Toshiba Medical Systems, Tokyo, Japan).

l-Carnitine improves cognitive and renal functions in a rat model of chronic kidney disease.

Over the past decade, the prevalence of chronic kidney disease (CKD) has reached epidemic proportions. The search for novel pharmacological treatment for CKD has become an area of intensive clinical research. l-Carnitine, considered as the "gatekeeper" responsible for admitting long chain fatty acids into cell mitochondria. l-Carnitine synthesis and turnover are regulated mainly by the kidney and its levels inversely correlate with serum creatinine of normal subjects and CKD patients. Previous studies showed that l-carnitine administration to elderly people is improving and preserving cognitive function. As yet, there are no clinical intervention studies that investigated the effect of l-carnitine administration on cognitive impairment evidenced in CKD patients. Thus, we aimed to investigate the effects of l-carnitine treatment on renal function and on the cognitive performance in a rat model of progressive CKD. To assess the role of l-carnitine on CKD condition, we estimated the renal function and cognitive abilities in a CKD rat model. We found that all CKD animals exhibited renal function deterioration, as indicated by elevated serum creatinine, BUN, and ample histopathological abnormalities. l-Carnitine treatment of CKD rats significantly reduced serum creatinine and BUN, attenuated renal hypertrophy and decreased renal tissue damage. In addition, in the two way shuttle avoidance learning, CKD animals showed cognitive impairment which recovered by the administration of l-carnitine. We conclude that in a rat model of CKD, l-carnitine administration significantly improved cognitive and renal functions.