Serum Lysyl Oxidase Is a Potential Diagnostic Biomarker for Kidney Fibrosis

Abstract

Background: Kidney fibrosis is the ultimate consequence of advanced stages of chronic kidney disease (CKD); however, there are currently no reliable biomarkers or noninvasive diagnostic tests available for the detection of kidney fibrosis. Lysyl oxidase (LOX) promotes collagen cross-linking, and serum LOX levels have been shown to be elevated in patients with fibrosis of the heart, lungs, and liver. However, serum LOX levels have not been reported in patients with kidney fibrosis. We explored whether serum LOX levels are associated with kidney fibrosis. Method: Overall, 202 patients with kidney disease underwent renal biopsy, scoring of kidney fibrosis, and determination of the area of kidney fibrosis. LOX levels were measured in serum and in kidney tissues. We analyzed the association of circulating LOX and tissue LOX levels with the scores and areas of kidney fibrosis. LOX expression was also investigated with in vitro and in vivo kidney fibrosis models. Results: Serum LOX levels were higher in patients with kidney fibrosis than in those without kidney fibrosis ( p < 0.001) and higher in patients with moderate-severe kidney fibrosis than in patients with mild kidney fibrosis ( p < 0.001). Both serum LOX and renal tissue LOX levels correlated with the area of kidney fibrosis ( r = 0.748, p < 0.001; r = 0.899, p < 0.001, respectively). Receiver operating characteristic curve analysis of serum LOX levels showed an area under the curve of 0.80 (95% CI: 0.74–0.86). The optimal serum LOX level cutoff point was 253.34 pg/mL for the prediction of kidney fibrosis and 306.56 pg/mL for the prediction of moderate-severe kidney fibrosis. LOX expression levels were significantly upregulated (2.3–2.6 and 6-fold, respectively) in in vitro and in vivo interstitial fibrosis models. Conclusions: Both serum LOX and tissue LOX levels correlated with the presence and degree of kidney fibrosis in patients with CKD. These results suggest that serum LOX levels could potentially serve as a noninvasive diagnostic biomarker for kidney fibrosis and may further potentially serve as a stratified biomarker for the identification of mild and moderate-severe kidney fibrosis.

Journal

Journal ID (publisher-id): AJN

Journal ID (nlm-ta): Am J Nephrol

Journal ID (doi): 10.1159/issn.0250-8095

Title: American Journal of Nephrology

Publisher: S. Karger AG

ISSN (Print): 0250-8095

ISSN (Electronic): 1421-9670

Publication date Subscription-year: 2020

Publication date (Print): December 2020

Publication date (Electronic): 05 November 2020

Volume: 51

Issue: 11

Pages: 907-918

Affiliations

_aDepartment of Nephrology, Tongji Hospital, Tongji University, Shanghai, China

_bDepartment of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden

Author notes

*Chen Yu, Department of Nephrology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065 (China), [e-mail]

Article

Publisher ID: 509381 Other ID: Am J Nephrol 2020;51:907–918

DOI: 10.1159/000509381

PubMed ID: 33152735

Copyright statement: © 2020 S. Karger AG, Basel

License:

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

Page count

Figures: 4, Tables: 3, Pages: 12

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Categories

Subject: Novel Research Findings