When Waldenström macroglobulinemia hits the kidney: Description of a case series and management of a "rare in rare" scenario.

BACKGROUND: Renal injury related to Waldenström macroglobulinemia (WM) occurs in approximately 3% of patients. Kidney biopsy is crucial to discriminate between distinct histopathological entities such as glomerular (amyloidotic and non-amyloidotic), tubulo-interstitial and non-paraprotein mediated renal damage. In this context, disease characterization, management, relationship between renal, and hematological response have been poorly explored. We collected clinical, genetic and laboratory data of seven cases of biopsy-proven renal involvement by WM managed at our academic center and focused on three cases we judged paradigmatic discussing their histopathological patterns, clinical features, and therapeutic options. CASE: In this illustrative case series, we confirm that serum creatinine levels and 24 h proteinuria are parameters that when altered should prompt the clinical suspicion of WM-related renal involvement, even if at present there are not precise cut-off levels recommending the execution of a renal biopsy. In our series AL Amyloidosis (n = 3/7) and tubulo-interstitial infiltration by lymphoma cells (n = 3/7) were the two more represented entities. BTKi did not seem to improve renal function (Case 1), while bortezomib-based regimens demonstrated a beneficial activity on the hematological and organ response, even when used as second-line therapy after chemoimmunotherapy (Case 3) and also with coexistence of anti-MAG neuropathy (Case 2). In case of poor response to bortezomib, standard chemoimmunotherapy (CIT), such as rituximab-bendamustine, represents an effective option (Case 1, 6, and 7). In our series, CIT generates durable responses more frequently in cases with amyloidogenic renal damage (Case 1, 5, and 7). CONCLUSION: In this illustrative case series, we confirm that serum creatinine levels and 24 h proteinuria are parameters that when altered should prompt the clinical suspicion of WM-related renal involvement, even if at present there are not precise cut-off levels recommending the execution of a renal biopsy. Studies with higher numerosity are needed to better clarify the pathological and clinical features of renal involvement during WM and to determine the potential benefit of different therapeutic regimens according to the histopathological subtypes.

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.

Pathophysiology of Post Transplant Hypertension in Kidney Transplant: Focus on Calcineurin Inhibitors Induced Oxidative Stress and Renal Sodium Retention and Implications with RhoA/Rho Kinase Pathway.

Post-transplant hypertension is a common occurrence during treatment with calcineurin inhibitors (CNIs) in kidney transplant population. The pathogenesis of vasoconstriction induced by CNIs involves vascular tone alterations and kidney sodium transport regulation. Among the factors involved a key role is played by the activation of intrarenal renin-angiotensin system with enhanced release of Angiotensin II (Ang II) and increase of oxidative stress. A common pathway between oxidative stress and hypertension induced by CNIs may be identified in the involvement of the activation of RhoA/Rho kinase pathway, key for the induction of hypertension and cardiovascular-renal remodeling, of the oxidative stress mediated increased nitric oxide (NO) metabolism and increased renal sodium retention via increased activity of thiazide-sensitive sodium chloride cotransporter (NCC) in the distal tubule. We examined literature data including those coming from our group regarding the role of oxidative stress and sodium retention in CNIs induced hypertension and their involvement in cardiovascular-renal remodeling. Based on the available data, we have provided support to the activation of RhoA/Rho kinase pathway as an important effector in the pathophysiology of CNIs induced post-transplant hypertension via activation of oxidative stress and sodium retention. Clarification of how the biochemical and molecular mechanisms that regulate the processes involved in CNIs induced post transplant hypertension work and interact, would provide further insights not only into the comprehension of the pathophysiology of CNIs induced post transplant hypertension but could also have a positive impact on the clinical ground through the identification of significant targets. Their specific pharmacologic targeting might have multiple beneficial effects on the whole cardiovascular-renal function. The demonstration that in kidney transplanted patients with CNIs induced post-transplanted hypertension, the treatment of hypertension with different antihypertensive drugs inducing a comparable blood pressure reduction but different effects for example on oxidative stress and oxidative stress related proteins and/or Rho kinase and sodium retention, could be helpful for the choice of the antihypertensive treatment in these patients which takes advantage from effects of these drugs beyond blood pressure reduction.

Increased rho kinase activity in mononuclear cells of dialysis and stage 3-4 chronic kidney disease patients with left ventricular hypertrophy: Cardiovascular risk implications.

AIMS: Cardiovascular disease (CVD) is the leading cause of excess mortality in chronic kidney disease (CKD) and dialysis patients (DP) who have higher prevalence of left ventricular hypertrophy (LVH), the strongest predictor of CV events. Rho kinase (ROCK) activation is linked in hypertensive patients to cardiac remodeling while ROCK inhibition suppresses cardiomyocyte hypertrophy and, in a human clinical condition opposite to hypertension, its downregulation associates with lack of CV remodeling. Information on ROCK activation-LVH link in CKD and DP is lacking. MATERIALS AND METHODS: Mononuclear cells (PBMCs) MYPT-1 phosphorylation, a marker of ROCK activity, and the effect of fasudil, a ROCK inhibitor, on MYPT-1 phosphorylation were assessed in 23 DPs, 13 stage 3-4 CKD and 36 healthy subjects (HS) by Western blot. LV mass was assessed by M-mode echocardiography. KEY FINDINGS: DP and CKD had higher MYPT-1 phosphorylation compared to HS (p<0.001 and p=0.003). Fasudil (500 and 1000µM) dose dependently reduced MYPT-1 phosphorylation in DP (p<0.01). DP had higher LV mass than CKD (p<0.001). MYPT-1 phosphorylation was higher in patients with LVH (p=0.009) and correlated with LV mass both in DP and CKD with LVH (p<0.001 and p=0.006). SIGNIFICANCE: In DP and CKD, ROCK activity tracks with LVH. This ROCK activation-LVH link provided in these CVD high-risk patients along with similar findings in hypertensive patients and added to opposite findings in a human model opposite to hypertension and in type 2 diabetic patients, identify ROCK activation as a potential LVH marker and provide further rationale for ROCK activation inhibition as target of therapy in CVD high-risk patients.

Intensive Home Hemodialysis: An Eye at the Past Looking for the Hemodialysis of the Future.

Multiple observational studies along with a limited number of randomized clinical trials suggest that intensive hemodialysis (IHD) not only improves outcomes for uremic patients undergoing chronic dialysis but does so with a more favorable cost/benefit ratio compared with conventional hemodialysis. As a result of this, there has been a rapid increase in the interest in home hemodialysis (HHD) as HHD represents the easiest means of implementing IHD. While HHD has generated increased interest given its association with better outcomes/reduced hospitalizations, there are very few randomized controlled trials comparing HHD with other hemodialysis methods. Reported HHD-associated increased survival benefits compared with in-center hemodialysis are from uncontrolled studies, which raise patient selection bias as underlying the differences found. Thus, while HHD draws increasing attention, studies that pay careful attention to the psychosocial, demographic, and clinical factors associated with patients selected to undergo HHD will be needed to ultimately demonstrate its benefits, clarify the clinical applications, and determine the limits of IHD use in dialysis patients.

Assessing the Relationship of Angiotensin II Type 1 Receptors with Erythropoietin in a Human Model of Endogenous Angiotensin II Type 1 Receptor Antagonism.

HYPOTHESIS/INTRODUCTION: Angiotensin II (Ang II) has been shown to control erythropoietin (EPO) synthesis as Ang II type 1 receptor (AT1R) blockers block Ang-II-induced EPO oversecretion. To further explore the involvement of AT1R in processes controlling EPO levels, plasma EPO and mononuclear cell NADPH oxidase 4 (NOX4) - a NOX family member involved in oxygen sensing, which is a process central to controlling EPO levels - were assessed in Bartter's/Gitelman's syndrome (BS/GS) patients, a human model of endogenous AT1R antagonism and healthy subjects. Heme oxygenase (HO)-1, antioxidant and anti-inflammatory factor related to NOX4 activation, and the relationship of EPO and NOX4 to HO-1 were also assessed. MATERIALS AND METHODS: EPO was measured by chemiluminescent immunoassay, HO-1 by sandwich immunoassay and NOX4 protein expression by Western blot. RESULTS: EPO was increased in BS/GS patients compared to healthy subjects (7.64 ± 2.47 vs. 5.23 ± 1.07 U/l; p = 0.025), whereas NOX4 did not differ between BS/GS and healthy subjects (1.76 ± 0.61 vs. 1.65 ± 0.54 densitometric units; p = n.s.), and HO-1 was increased in BS/GS patients compared to healthy subjects (9.58 ± 3.07 vs. 5.49 ± 1.04 ng/ml; p = 0.003). NOX4 positively correlated with HO-1 only in BS/GS patients; no correlation was found between EPO and either NOX4 or HO-1 in those two groups. CONCLUSIONS: The effect of the renin-angiotensin system on EPO cannot be solely mediated by Ang II via AT1R signaling, but rather, EPO levels are also determined by a complex interrelated set of signals that involve AT2R, nitric oxide levels, NOX4 and HO-1 activity.