Enzymatically Modified LDL Induces Cathepsin H in Human Monocytes

Han, Shan-Rui; Momeni, Arash; Strach, Katharina; Suriyaphol, Prapat; Fenske, Dominic; Paprotka, Kerstin; Hashimoto, Shin Ichi; Torzewski, Michael; Bhakdi, Sucharit; Husmann, Matthias

doi:10.1161/01.atv.0000063614.21233.bf

Cited by 32 publications

(23 citation statements)

References 44 publications

(36 reference statements)

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“…eLDL generated by all tested proteases is endowed with the same atherogenic properties as the originally described trypsin‐generated eLDL 23, 31. Evidence for the presence of proteases like matrix metalloproteinases or cathepsins in aortic valve sclerosis is abundant 4.…”

Section: Discussionmentioning

confidence: 77%

Enzymatically Modified Low‐Density Lipoprotein Is Present in All Stages of Aortic Valve Sclerosis: Implications for Pathogenesis of the Disease

Twardowski

Cheng

Michaelsen

et al. 2015

JAHA

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BackgroundWe have demonstrated previously that enzymatically degraded low‐density lipoprotein (eLDL) is an essential causative component for the initiation of atherosclerosis. Here, we investigated the different stages of human aortic valve sclerosis for the presence of eLDL and effectors of the innate immune system, as well as the interaction of eLDL with isolated valvular interstitial cells/myofibroblasts to discover possible pathways leading to aortic valve sclerosis.Methods and ResultsHuman aortic valvular tissue was obtained from 68 patients undergoing valve replacement surgery. Patients were classified into 3 groups (mild, moderate, or severe aortic valve sclerosis), and clinical data for statistical analysis were gathered from all patients. Immunohistochemical staining demonstrated extensive extracellular deposits of eLDL throughout all grades of aortic valve sclerosis. Complementary analysis of lipid composition revealed higher concentrations of the decisive components of eLDL (ie, unesterified cholesterol and linoleic acid) compared with internal control tissues. Further, the complement component C3d and terminal complement complexes colocalized with eLDL compatible with the proposal that subendothelially deposited eLDL is enzymatically transformed into a complement activator at early stages of valvular cusp lesion development. Gene expression profiles of proteases and complement components corroborated by immunohistochemistry demonstrated an upregulation of the protease cathepsin D (a possible candidate for LDL degradation to eLDL) and the complement inhibitor CD55. Surprisingly, substantial C‐reactive protein expression was not observed before grade 2 aortic valve sclerosis as investigated with microarray analysis, reverse transcription–polymerase chain reaction analysis, and immunohistochemistry. Finally, we demonstrated cellular uptake of eLDL by valvular interstitial cells/myofibroblasts.ConclusionsThe present study is a startup of a hypothesis on the pathogenesis of aortic valve sclerosis declaring extracellular lipoprotein modification, subsequent complement activation, and cellular uptake by valvular interstitial cells/myofibroblasts as integral players.

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Section: Discussionmentioning

confidence: 77%

Enzymatically Modified Low‐Density Lipoprotein Is Present in All Stages of Aortic Valve Sclerosis: Implications for Pathogenesis of the Disease

Twardowski

Cheng

Michaelsen

et al. 2015

JAHA

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“…Thus, cathepsin H was detected by immunohistochemistry in colocalization with E-LDL, and E-LDL produced in vitro with this protease potently induced macrophage foam cell formation. 29 It was now satisfying to find that E-LDL prepared with plasmin also had the same complement-activating properties. Together, the findings provide persuasive evidence that several tissuelocated proteinases can generate E-LDL.…”

Section: Discussionmentioning

confidence: 99%

“…9,16,28,29 Rigorous controls involving complete removal of staining by prior absorption of primary antibodies with the respective isolated antigen were done for antibodies against E-LDL and CRP, as previously described. 9,30 An irrelevant isotype-matched antibody directed against Aspergillus niger glucose oxidase (clone DAK-GO-1) and normal rabbit serum (DakoCytomation, X0936) were used to control staining specificity of the C5b-9 antibody and C3d antibody, respectively.…”

Section: Immunohistochemistrymentioning

confidence: 99%

Possible Protective Role for C-Reactive Protein in Atherogenesis

et al. 2004

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Background-Previous work indicated that enzymatically remodeled LDL (E-LDL) might activate complement in atherosclerotic lesions via a C-reactive protein (CRP)-dependent and CRP-independent pathway. We sought to substantiate this contention and determine whether both pathways drive the sequence to completion. Methods and Results-E-LDL was prepared by sequential treatment of LDL with a protease and cholesteryl esterase.Trypsin, proteinase K, cathepsin H, or plasmin was used with similar results. Functional tests were used to assess total complement hemolytic activity, and immunoassays were used to demonstrate C3 cleavage and to quantify C3a, C4a, C5a, and C5b-9. E-LDL preparations activated complement to completion, independent of CRP, when present above a threshold concentration (100 to 200 g/mL in 5% serum). Below the threshold, all E-LDL preparations activated complement in dependence of CRP, but the pathway then halted before the terminal sequence. Native LDL and oxidized LDL did not activate complement under any circumstances tested. Immunohistological analyses corroborated the concept that CRP-dependent complement activation inefficiently generates C5b-9. Conclusions-Binding of CRP to E-LDL is the first trigger for complement activation in the atherosclerotic lesion, but the terminal sequence is thereby spared. This putatively protective function of CRP is overrun at higher E-LDL concentrations, so that potentially harmful C5b-9 complexes are generated.

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“…8,9 Combined treatment of LDL with a protease and cholesterylesterase in vitro generates an LDL-derivative (E-LDL) with the same chemical, functional and micromorphological properties. 10 LDL-modifying proteases [11][12][13] as well as cholesterylesterase 12 have been detected in atherosclerotic lesions, where they colocalize with enzymatically modified LDL, C-reactive protein (CRP) and complement. 11,14,15 These findings indicate that nonoxidative, enzymatic remodeling of LDL occurs at the early stages of atherogenesis.…”

Section: Introductionmentioning

confidence: 99%

“…10 LDL-modifying proteases [11][12][13] as well as cholesterylesterase 12 have been detected in atherosclerotic lesions, where they colocalize with enzymatically modified LDL, C-reactive protein (CRP) and complement. 11,14,15 These findings indicate that nonoxidative, enzymatic remodeling of LDL occurs at the early stages of atherogenesis. We are submitting for discussion that this modification is not primarily harmful, but that it may be physiological and meaningful because the lipoprotein could thus be able to signal to the immune system and effect its own removal.…”

Section: Introductionmentioning

confidence: 99%

Fatty acids liberated from low-density lipoprotein trigger endothelial apoptosis via mitogen-activated protein kinases

et al. 2005

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Enzymatic modification of low-density lipoprotein (LDL) as it probably occurs in the arterial intima drastically increases its cytotoxicity, which could be relevant for the progression of atherosclerotic lesions. LDL was treated with a protease and cholesterylesterase to generate a derivative similar to lesional LDL, with a high content of free cholesterol and fatty acids. Exposure of endothelial cells to the enzymatically modified lipoprotein (E-LDL), but not to native or oxidized LDL, resulted in programmed cell death. Apoptosis was triggered by apoptosis signal-regulating kinase 1 dependent phosphorylation of p38. Depletion and reconstitution experiments identified free fatty acids (FFA) as the triggers of this pathway. Levels of FFA in native LDL are low and the lipoprotein is therefore not cytotoxic; enzymatic cleavage of cholesterylesters liberates FFA that can rapidly trigger an apoptosis signaling cascade in neighboring cells. Blockade of this pathway can rescue cells from death.

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Enzymatically Modified LDL Induces Cathepsin H in Human Monocytes

Abstract: Objective-Modification with proteases and cholesterylesterase transforms LDL to a moiety that resembles lipoproteins isolated from atherosclerotic lesions and possesses atherogenic properties.

Cited by 32 publications

References 44 publications

Enzymatically Modified Low‐Density Lipoprotein Is Present in All Stages of Aortic Valve Sclerosis: Implications for Pathogenesis of the Disease

Enzymatically Modified Low‐Density Lipoprotein Is Present in All Stages of Aortic Valve Sclerosis: Implications for Pathogenesis of the Disease

Possible Protective Role for C-Reactive Protein in Atherogenesis

Fatty acids liberated from low-density lipoprotein trigger endothelial apoptosis via mitogen-activated protein kinases

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