Identification of a Lipid Peroxidation Product as the Source of Oxidation-specific Epitopes Recognized by Anti-DNA Autoantibodies*

Abstract

Lipid peroxidation in tissue and in tissue fractions represents a degradative process, which is the consequence of the production and the propagation of free radical reactions primarily involving membrane polyunsaturated fatty acids, and has been implicated in the pathogenesis of numerous diseases, including systemic lupus erythematosus (SLE). We have found that bovine serum albumin incubated with peroxidized polyunsaturated fatty acids significantly cross-reacted with the sera from MRLlpr mice, a representative murine model of SLE. To identify the active substances responsible for the generation of autoantigenic epitopes recognized by the SLE sera, we performed the activity-guiding separation of a principal source from 13-hydroperoxy-9Z,11E-octadecadienoic acid and identified 4-oxo-2-nonenal (ONE), a highly reactive aldehyde originating from the peroxidation of 6 polyunsaturated fatty acids, as the source of the autoantigenic epitopes. When the age-dependent change in the antibody titer against the ONE-modified protein was measured in the sera from MRL-lpr mice and control MRL-MpJ mice, all of the MRL-lpr mice developed an anti-ONE titer, which was comparable with the anti-DNA titer. Strikingly, a subset of the anti-DNA monoclonal antibodies generated from the SLE mice showing recognition specificity toward DNA cross-reacted with the ONE-specific epitopes. Furthermore, these dual-specific antibodies rapidly bound and internalized into living cells. These findings raised the possibility that the enhanced lipid peroxidation followed by the generation of ONE may be involved in the pathogenesis of autoimmune disorders.

Antibodies to post-translationally modified insulin in type 1 diabetes

“…It is interesting to note that one of the observed modifications involving chlorination of Tyr16 of chain B (Tyr B16) is within the region 9-23 of chain B (B:9-23), a known dominant epitope in autoimmune diabetes [21], with Tyr16 being crucial in immunoreactivity. Substitution of Tyr in position 16 to Ala (Tyr B16:Ala) has been shown to abrogate T cell reactivity [22,23], and administration of a modified B:9-23 (Tyr B16:Ala) peptide has been reported to suppress expression of IAA and prevent diabetes in the NOD mouse [24]; conversely, it is possible that Tyr16 modification by HOCl oxPTM by ROS appears to play a key role in the pathogenesis of several human autoimmune diseases [13,[25][26][27]. This is of particular relevance to type 1 diabetes, where islet inflammation and the ensuing hyperglycaemia are substantial sources of ROS production [2,5].…”

Oxidative stress in the pathology and treatment of systemic lupus erythematosus

“…96 In the MRL/lpr mouse model of SLE, the reactive aldehyde 4-oxo-2-nonenal (ONE) was identified as a source of autoantigenic epitopes and autoimmunity. 97 Bovine serum albumin became crossreactive with sera from the mice after it was incubated with peroxidized polyunsaturated fatty acids; anti-ONE reactivity was detected and a subset of anti-DNA antibodies in the mice was found to be crossreactive with ONE-specific epitopes. 97 …”

“…Evidence for the propagation of oxidative autoantigenesis through the circulation, and how this process triggers inflammation, organ damage and comorbidities in SLE is discussed in this section. Oxidative autoantigenic processes relevant to SLE include: the accumulation of oxidized HDL cholesterol (oxHDL) in the blood; oxidation of β2 glycoprotein I (β2GPI); 96 modification of polyunsaturated fatty acids and generation of autoantibodies crossreactive with DNA; 97 and UV light-triggered autoantigenicity of Ro. 98 …”

Chemistry and analysis of HNE and other prominent carbonyl-containing lipid oxidation compounds

“…Several studies on ONE concurred in concluding that it is an even more reactive protein modification and cross-linking agent than HNE [55], although interestingly, its reactivity appears to differ: the rate of Michael adduct formation with cysteine (cys) and histidine (his) is higher but the rate of Schiff base formation is actually slower [56]. Biologically relevant adducts with histones [57] and human serum albumin [58] have been demonstrated recently and have increased attention on this aldehyde as an oxidative stress marker. While OHE was initially reported from studies in vitro and detected in food, there has been interest in its mutagenic properties, which are thought to arise from its reactivity and ability to form adducts with nucleosides [54,55].…”