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Harmacek D, Weidmann L, Castrezana Lopez K, Schmid N, Korach R, Bortel N, von Moos S, Rho E, Helmchen B, Gaspert A, Schachtner T. Molecular diagnosis of antibody-mediated rejection: Evaluating biopsy-based transcript diagnostics in the presence of donor-specific antibodies but without microvascular inflammation, a single-center descriptive analysis. Am J Transplant 2024:S1600-6135(24)00244-2. [PMID: 38548057 DOI: 10.1016/j.ajt.2024.03.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/19/2024]
Abstract
Biopsy-based transcript diagnostics may identify molecular antibody-mediated rejection (AMR) when microvascular inflammation (MVI) is absent. In this single-center cohort, biopsy-based transcript diagnostics were validated in 326 kidney allograft biopsies. A total of 71 histological AMR and 35 T cell-mediated rejection (TCMR) cases were identified as molecular AMR and TCMR in 55% and 63%, respectively. Among 121 cases without MVI (glomerulitis + peritubular capillaritis = 0), 45 (37%) donor-specific antibody (DSA)-positive and 76 (63%) DSA-negative cases were analyzed. Twenty-one out of the 121 (17%) cases showed borderline changes, or TCMR, while BK nephropathy was excluded. None of the 45 DSA-positive patients showed molecular AMR. Among 76 DSA-negative patients, 2 had mixed molecular AMR/TCMR. All-AMR phenotype scores (sum of R4-R6) exhibited median values of 0.13 and 0.12 for DSA-positive and DSA-negative patients, respectively (P = .84). A total of 13% (6/45) DSA-positive and 11% (8/76) DSA-negative patients showed an all-AMR phenotype score > 0.30 (P = .77). Patients with a higher all-AMR phenotype score showed 33% more histologic TCMR (P = .005). The median all-AMR phenotype scores of glomerular basement membrane double contours = 0 and glomerular basement membrane double contours > 0 biopsies were 0.12 and 0.10, respectively (P = .35). Biopsy-based transcript diagnostics did not identify molecular AMR in cases without MVI. Follow-up biopsies and outcome data should evaluate the clinical relevance of subthreshold molecular alterations.
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Affiliation(s)
- Dusan Harmacek
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Lukas Weidmann
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | | | - Nicolas Schmid
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Raphael Korach
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Nicola Bortel
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Seraina von Moos
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Elena Rho
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Birgit Helmchen
- Institute of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Ariana Gaspert
- Institute of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Thomas Schachtner
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland.
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Harmacek D, Bonny O. Sodium/glucose cotransporter 2 inhibition and urolithiasis: the effect of urinary pH and citrate. Kidney Int Rep 2023. [DOI: 10.1016/j.ekir.2023.02.1094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
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Harmacek D, Pruijm M, Burnier M, Muller ME, Ghajarzadeh-Wurzner A, Bonny O, Zanchi A. Empagliflozin Changes Urine Supersaturation by Decreasing pH and Increasing Citrate. J Am Soc Nephrol 2022; 33:1073-1075. [PMID: 35387874 PMCID: PMC9161803 DOI: 10.1681/asn.2021111515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Clinical Trial registry name and registration number: Empagliflozin and Renal Oxygenation in Healthy Volunteers (EMPA-REIN), NCT03093103.
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Affiliation(s)
- Dusan Harmacek
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Menno Pruijm
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Michel Burnier
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Marie-Eve Muller
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Arlène Ghajarzadeh-Wurzner
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Olivier Bonny
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland.,Service of Nephrology, Department of Medicine, Fribourg State Hospital, Fribourg, Switzerland
| | - Anne Zanchi
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
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Ansermet C, Centeno G, Pradervand S, Harmacek D, Garcia A, Daraspe J, Kocherlakota S, Baes M, Bignon Y, Firsov D. Renal tubular peroxisomes are dispensable for normal kidney function. JCI Insight 2022; 7:155836. [PMID: 35191396 PMCID: PMC8876468 DOI: 10.1172/jci.insight.155836] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/12/2022] [Indexed: 12/04/2022] Open
Abstract
Peroxisomes are specialized cellular organelles involved in a variety of metabolic processes. In humans, mutations leading to complete loss of peroxisomes cause multiorgan failure (Zellweger’s spectrum disorders, ZSD), including renal impairment. However, the (patho)physiological role of peroxisomes in the kidney remains unknown. We addressed the role of peroxisomes in renal function in mice with conditional ablation of peroxisomal biogenesis in the renal tubule (cKO mice). Functional analyses did not reveal any overt kidney phenotype in cKO mice. However, infant male cKO mice had lower body and kidney weights, and adult male cKO mice exhibited substantial reductions in kidney weight and kidney weight/body weight ratio. Stereological analysis showed an increase in mitochondria density in proximal tubule cells of cKO mice. Integrated transcriptome and metabolome analyses revealed profound reprogramming of a number of metabolic pathways, including metabolism of glutathione and biosynthesis/biotransformation of several major classes of lipids. Although this analysis suggested compensated oxidative stress, challenge with high-fat feeding did not induce significant renal impairments in cKO mice. We demonstrate that renal tubular peroxisomes are dispensable for normal renal function. Our data also suggest that renal impairments in patients with ZSD are of extrarenal origin.
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Affiliation(s)
| | | | | | | | | | - Jean Daraspe
- Electron Microscopy Facility, University of Lausanne, Lausanne, Switzerland
| | - Sai Kocherlakota
- Department for Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium
| | - Myriam Baes
- Department for Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium
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Harmacek D, Blanchard A, Wuerzner G, Maillard M, Jeunemaitre X, Azizi M, Bonny O. Acute decrease of urine calcium by amiloride in healthy volunteers under high sodium diet. Nephrol Dial Transplant 2021; 37:298-303. [PMID: 33914065 DOI: 10.1093/ndt/gfab159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Amiloride is a competitive blocker of the epithelial sodium channel (ENaC) in the renal collecting duct. It is a less potent diuretic than thiazides or loop diuretics, but is often used in association for its potassium-sparing profile. Whether amiloride has hypocalciuric effect similar to thiazides remains unclear. Animal studies and experiments on cell lines suggested that amiloride increases calcium reabsorption in the distal nephron, but human studies are scarce. METHODS We performed a post hoc analysis of a study with 48 healthy males (age, 23.2 ± 3.9 years) who were assigned to a high sodium (Na)/low potassium (K) diet for 7 days before receiving 20 mg of amiloride p.o. Urinary excretions of electrolytes were measured at 3 and 6 hours afterward; we calculated the relative changes in urinary excretion rates after amiloride administration. RESULTS The high Na/low K diet led to an expected suppression of plasma renin and aldosterone. Amiloride showed a mild natriuretic effect associated with a decreased kaliuresis. Urinary calcium excretion dropped substantially (by 80%) 3 hours after amiloride administration and remained low at the 6th hour. At the same time, fractional excretion of lithium decreased by a third, reflecting an increased proximal tubular reabsorption. CONCLUSION During a high Na/low K diet, amiloride had a strong acute hypocalciuric effect, most probably mediated by increased proximal calcium reabsorption, even though distal effect cannot be excluded. Further studies should establish if chronic amiloride or combined amiloride/thiazide treatment may decrease calciuria more efficiently and be useful in preventing kidney stones.
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Affiliation(s)
- Dusan Harmacek
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Anne Blanchard
- INSERM, CIC1418, F-75015, Paris, France; Université de Paris, F-75006, Paris, France; AP-HP, Hôpital Européen Georges-Pompidou, DMU CARTE, F-75015, Paris, France
| | - Gregoire Wuerzner
- Service of Nephrology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Marc Maillard
- Service of Nephrology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Xavier Jeunemaitre
- Université de Paris, Inserm U970 PARCC, F-75006, Paris, France and APHP, Service de Génétique, Hôpital Européen Georges Pompidou, F-75015, Paris, France
| | - Michel Azizi
- Université de Paris, F-75006, Paris, France; AP-HP, Hôpital Européen Georges-Pompidou, Hypertension Department and DMU CARTE, F-75015, Paris, France; INSERM, CIC1418, F-75015, Paris, France
| | - Olivier Bonny
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland and Service of Nephrology, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
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Abstract
Arteriosklerosis and "osteoporosis" in patients with chronic kidney disease: same same, but different! Abstract. Vascular calcifications should be considered a dynamic process sharing many similarities with bone formation. Even though the underlying pathophysiology of renal insufficiency-related vascular and bone disorders has just begun to be revealed, they appear to be closely related to each other and together appear to have an enormous impact on cardiovascular morbidity and mortality. Vascular and bone disorders are highly prevalent in the general population. In patients with chronic kidney disease (CKD), not only the progression of these disorders appears to be accelerated, but they also appear to be governed by different pathophysiological mechanisms, and hence should be managed differently. One should be especially cautious about the use of some "standard drugs" like calcium supplements or bisphosphonates when treating patients with CKD. Unfortunately, no evidence-based therapeutic options of vascular and bone disorders in patients with CKD are yet available with proven positive effect on hard endpoints such as overall mortality or fracture risk.
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Affiliation(s)
- Dusan Harmacek
- 1 Klinik für Nephrologie und Hypertonie, Universitätsspital Inselspital Bern
| | - Spiros Arampatzis
- 1 Klinik für Nephrologie und Hypertonie, Universitätsspital Inselspital Bern
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