ORIGINAL PAPER Serum methylglyoxal level and its association with oxidative stress and disease severity in patients with psoriasis Sirje Kaur • Kersti Zilmer • Vambola Leping • Mihkel Zilmer Received: 12 February 2013 / Revised: 18 April 2013 / Accepted: 22 April 2013 / Published online: 1 May 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Psoriasis vulgaris (PV), a chronic inflammatory skin disease, is a condition of increased oxidative stress (OxS). However, interest related to oxidative and carbonyl stress damages to proteins, such as the formation of advanced glycation end products (AGEs) and their precursor molecule methylglyoxal (MG) has been modest. The objective of this study was to compare the systemic levels of OxS markers in patients with PV and healthy controls (Co) and to investigate their correlation with the serum level of MG. Total peroxide concentration (TPX) and total antioxidant capacity (TAC) were estimated by means of spectrophotometry. The TPX and TAC ratio was regarded as OxS index (OSI). MG level was determined using ELISA. Compared to Co, patients with PV had significantly increased blood levels of TPX (P \ 0.0001), OSI (P \ 0.0001), and MG (P = 0.01), and lower TAC levels (P \ 0.0001). Increase in body mass index (BMI) appeared to contribute to this imbalance as TAC levels decreased with increasing BMI (r =-0.252, P \ 0.01). Increased TPX concentration was associated with higher serum level of MG (r = 0.610, P = 0.004), the latter being positively correlated with psoriasis area and severity index (r = 0.577, P = 0.008). In performed multivariate regression analysis, TPX, TAC, and OSI were all significant predictors of MG level. Our study gave further proof of increased systemic psoriasis-related OxS. MG serum level, reflecting simultaneously OxS as well as carbonyl stress status, could be used as a marker of disease activity in clinical trials while looking for new systemic therapies for psoriasis. Keywords Methylglyoxal Á Total peroxide concentration Á Total antioxidant capacity Á Oxidative stress index, Psoriasis area and severity index Introduction Increased systemic inflammation and oxidative stress (OxS) have been established in patients with psoriasis [2, 11, 22, 32]. However, the role of OxS in psoriasis seems to be underestimated, especially considering its close con- nections with carbonyl stress and related damages to proteins. A major cause of spontaneous damage to proteins in physiological systems is glycation [1], a process where amino acids in proteins are non-enzymatically modified by reducing sugars [27]. Over time, early glycation products undergo progressive modification to the formation of irre- versible cross-linked molecules termed ‘‘advanced glyca- tion end products’’ (AGEs) [27]. In addition, AGEs may form through several other pathways, including oxidation of sugars, lipids, and amino acids to create reactive alde- hydes that covalently bind to proteins [23]. AGEs are nearly irreversible and accumulate in the tissue altering cellular structure and function [4, 14]. The formation of AGEs occurs permanently in physiological terms, e.g., aging [4, 24]. It is markedly amplified in diabetes as a consequence of hyperglycemia, but also in several diseases in patients with normal blood glucose level [23], e.g., other S. Kaur (&) Clinic of Dermatology, University of Tartu, 31 Raja St, 50417 Tartu, Estonia e-mail: Sirje.Kaur@kliinikum.ee K. Zilmer Á M. Zilmer Institute of Biochemistry, the Centre of Excellence for Translational Medicine, University of Tartu, Tartu, Estonia V. Leping Institute of Computer Sciences, University of Tartu, Tartu, Estonia 123 Arch Dermatol Res (2013) 305:489–494 DOI 10.1007/s00403-013-1362-5