Acrolein accumulation

Acrolein is an unsaturated aldehyde created through both endogenous and exogenous means. Acrolein is a metabolite in lipid peroxidation, can be synthesized for commercial use, and can also become a metabolite in some substrate detoxification (Uchida et.al., 1998, Ibrahim, et al., 2023). Acrolein accumulation has been known to lead to oxidative stress through the generation of reactive oxygen species as well as form acrolein -protein or acrolein-DNA adducts thus leading to cell damage, apoptosis, mitochondrial disfunction or cancer (Hong et.al, 2020, Ibrahim, et al., 2023, Burcham et al., 2006, Luo et al., 2007). On an organ level, acrolein-induced oxidative stress is associated with severe toxicity in the renal system (Moghe et al., 2015). 

Protein adducts: Acrolein is a strong electrophile (electron-loving) and is high reactivity with cellular nucleophiles such as proteins, DNA and RNA. As such, acrolein readily targets the sulfhydryl group of cysteine, the imidazole group of histidine, and the amino group of lysine which results in the acrolein-protein connections via these amino acids. The accumulation of acrolein protein adducts can result in improper protein folding and also lead to ER stress (Moghe et al., 2015). One major data gap is that the mechanisms by which acrolein induces ER stress remain unknown but may be a combination of oxidative stress, protein, or DNA adduct formation (Haberzettl et al., 2008).

DNA adducts:  Acrolein can cause DNA damage through many pathways such as (Reactive oxygen species) ROS production and adduct formation which have both been linked to mutations and carcinogenesis. Acrolein being very electrophilic can create cross-links of double-stranded DNA as well as DNA-protein cross-links. Acrolein readily reacts with deoxyguanosine (dG) producing two exocyclic DNA adducts, α- and γ-hydroxy-1, N2-propano-2′-deoxyguanosine (α-HOPdG and γ-HOPdG), which have been linked to mutations (Tang et al., 2011). There have also been reports of acrolein adducts with  2′-deoxyadenosine, 2-deoxycytidine DNA bases, and thymidine. This adduct formation has been studied both in vitro and in vivo in several animal tissues, human tissues, and cells (Tang et al., 2011; Voulgaridou et al., 2011).

Oxidative stress: Many processes such as bioactivation and mitochondrial cellular respiration produce ROS like superoxide which can damage lipids, proteins, carbohydrates, and nucleic acids. This damage occurs when highly Some endogenous and exogenous remedies to reactive oxygen species are antioxidant compounds like vitamin C and antioxidant enzymes like superoxide dismutase (SOD). The imbalance of ROS can overwhelm these defense mechanisms, which in turn results in a phenomenon called oxidative stress (Moghe et al., 2015). In vivo and in vitro studies confirm that acrolein can itself cause oxidative damage, leading DNA and mitochondrial damage and can exacerbate apoptosis. Acrolein exposure has been seen to significantly increase oxidant levels by decreasing the antioxidant glutathione, anti-oxidant enzymes (SOD and GSH-peroxidase), and total and nuclear levels of the antioxidant regulator-Nrf2 (Moghe et al., 2015).

Inflammation: Acrolein has been seen to not only be a product of lipid peroxidation but also an initiator for some inflammatory pathways. For instance, some studies have shown acrolein can activate NF-κB and induce proinflammatory mediators in rat lung epithelial cells from only acute acrolein exposure. Acrolein exposure was seen to induce the NF-κB dependent marker of inflammation, COX-2 via calcium release and subsequent proteolytic degradation of IκBα. (Sarkar and Hayes, 2007). In addition. inflammatory IL-8 upregulation is associated with many inflammatory disorders, and IL-8 production due to acrolein exposure has been studied in vitro in multiple cell types, including multiple human cells (Moghe et al., 2015).  

•    Mass Spectroscopy: Gas and liquid chromatography tandem mass spectroscopy (Lc-MS and GC-MS) have been used to separate and detect acrolein adducts and other lipid peroxidation markers in humans. Samples containing acrolein are first cleaned by extractions (either solid phase or solvent extractions depending on the sample type) and purified further via LC or GC, following this the mass to charge ratio of acrolein can be viewed via mass spectroscopy. One easy and notable way is electronspray ionization mass spectroscopy (Uchida et.al., 1998). With those detection methods in mind, there are many ways to sample acrolein-adducts such as blood, saliva, tissue, and urine samples (Hirose et al., 2015, Hikisz & Jacenik 2023, Bispo et al., 2016). 

•    Spectroscopy: The characteristic absorbance of acrolein-adduct formation has also been studied and used as a preliminary qualitative screen for further quantitative testing in some studies. The fundamentals of this method has been studied through both testing in human samples and simulation of the protein adduct formation in vivo. The simulation includes reacting a sample containing acrolein with Nα-acetyllysine or Nα-acetylhistidine  to create protein-acrolein adducts, purifying the sample with liquid chromatography, then measuring the absorbance at the respective wavelength depedning on the adduct of interest (Uchida et.al., 1998).

•    Immunoblotting: Acrolein-protein adducts can be separated and measured with techniques such as western blotting or enzyme linked immunosorbent assays, also know as ELISA's (Chen et al., 2016). These techniques both include exposing proteins to a primary anti-body specific to the acrolein adduct of interest, followed by washing and the addition of a secondary antibody. The outcome of these exposures and therefore presence of acrolein adducts can be read through chemiluminescent reactions. For ELISA this is done through an ELISA microplate reader and for western blotting through membrane imagine apparatus (Uchida et.al., 1998). 

•    Histology:  When a tissue sample is obtained another method used to measure or detect acrolein presence via adducts is histology. In this method a sample of cross sectioned tissue is obtained, fixed, and stained with polyclonal antibodies specific for the acrolein adduct of interest. Following this, the tissue can be examined via light microscopy for the appearance of acrolein adducts and quantified using imaging software. This technique can also be applied to certain cells such as most hepatocytes (Chen et al., 2016).    

• D: Taxonomic applicability:  Most data was generated from human studies, rat, or mice studies (Uchida et. al., 1998, Wang et al., 2012, Chen et al., 2016).
• E: Life stages: The domain of applicability for life stages is all life stages. 
• F: Sex applicability: The domain of applicability for sex is both males and females.

Bispo VS, de Arruda Campos IP, Di Mascio P, Medeiros MH. (2016) Structural Elucidation of a Carnosine-Acrolein Adduct and its Quantification in Human Urine Samples. Sci Rep. 19;6:19348. 

Burcham PC, Pyke SM. Hydralazine inhibits rapid acrolein-induced protein oligomerization: role of aldehyde scavenging and adduct trapping in cross-link blocking and cytoprotection. Mol Pharmacol. 2006;69:1056–1065.

Chen WY, Zhang J, Ghare S, Barve S, McClain C, Joshi-Barve S. (2016) Acrolein Is a Pathogenic Mediator of Alcoholic Liver Disease and the Scavenger Hydralazine Is Protective in Mice. Cell Mol Gastroenterol Hepatol. 27;2(5):685-700.

Haberzettl P, Vladykovskaya E, Srivastava S, Bhatnagar A. Role of endoplasmic reticulum stress in acrolein-induced endothelial activation. Toxicol Appl Pharmacol. 2009 Jan 1;234(1):14-24

Hikisz, P.; Jacenik, D. (2023) Diet as a Source of Acrolein: Molecular Basis of Aldehyde Biological Activity in Diabetes and Digestive System Diseases. Int. J. Mol. Sci. , 24, 6579.

Hirose T, Saiki R, Uemura T, Suzuki T, Dohmae N, Ito S, Takahashi H, Ishii I, Toida T, Kashiwagi K, Igarashi K. (2015) Increase in acrolein-conjugated immunoglobulins in saliva from patients with primary Sjögren's syndrome. Clin Chim Acta. 450:184-9. 

Ibrahim, K.M., Darwish, S.F., Mantawy, E.M. et al. Molecular mechanisms underlying cyclophosphamide-induced cognitive impairment and strategies for neuroprotection in preclinical models. Mol Cell Biochem (2023).

Jian-Hua Hong, Priscilla Ann Hweek Lee, Yu-Chuan Lu, Cheng-Yu Huang, Chung-Hsin Chen, Chih-Hung Chiang, Po-Ming Chow, Fu-Shan Jaw, Chung-Chieh Wang, Chao-Yuan Huang, Tse-Wen Wang, Jin-Hui Liu, Hsiang-Tsui Wang, (2020) Acrolein contributes to urothelial carcinomas in patients with chronic kidney disease, Urologic Oncology: Seminars and Original Investigations, 38 (5) 465-475,

Koji Uchida, Masamichi Kanematsu, Yasujiro Morimitsu, Toshihiko Osawa, Noriko Noguchi, Etsuo Niki, (1998) Acrolein Is a Product of Lipid Peroxidation Reaction: FORMATION OF FREE ACROLEIN AND ITS CONJUGATE WITH LYSINE RESIDUES IN OXIDIZED LOW DENSITY LIPOPROTEINS*, Journal of Biological Chemistry.

Luo J, Hill BG, Gu Y, Cai J, Srivastava S, Bhatnagar A, Prabhu SD. (2007 )Mechanisms of acrolein-induced myocardial dysfunction: implications for environmental and endogenous aldehyde exposure. Am J Physiol Heart Circ Physiol.

Moghe A, Ghare S, Lamoreau B, Mohammad M, Barve S, McClain C, Joshi-Barve S. (2015) Molecular mechanisms of acrolein toxicity: relevance to human disease. Toxicol Sci. ;143(2):242-55.

Sarkar P., Hayes B. E. (2007). Induction of COX-2 by acrolein in rat lung epithelial cells. Mol. Cell. Biochem. 301, 191–199.

Tang M. S., Wang H. T., Hu Y., Chen W. S., Akao M., Feng Z., Hu W. (2011). Acrolein induced DNA damage, mutagenicity and effect on DNA repair. Mol. Nutr. Food Res. 55, 1291–1300

Voulgaridou G. P., Anestopoulos I., Franco R., Panayiotidis M. I., Pappa A. (2011). DNA damage induced by endogenous aldehydes: current state of knowledge. Mutat. Res. 711, 13–27

Wang SP, Chen YH, Li H. (2012) Association between the levels of polyunsaturated fatty acids and blood lipids in healthy individuals. Exp Ther Med. 4(6):1107-1111.