Chronic or intermittent hyperglycemia is associated with the development of diabetic complications. Several signaling pathways can be altered by having hyperglycemia in different tissues, producing oxidative stress, the formation of advanced glycation end products (AGEs), as well as the secretion of the pro-inflammatory cytokines and cellular death (pathological autophagy and/or apoptosis). However, the signaling pathways that are directly triggered by hyperglycemia appear to have a pivotal role in diabetic complications due to the production of reactive oxygen species (ROS), oxidative stress, and cellular death. The present review will discuss the role of cellular death in diabetic complications, and it will suggest the cause and the consequences between the hyperglycemia-induced signaling pathways and cell death. The signaling pathways discussed in this review are to be described step-by-step, together with their respective inhibitors. They involve diacylglycerol, the activation of protein kinase C (PKC) and NADPH-oxidase system, and the consequent production of ROS. This was initially entitled the “dangerous metabolic route in diabetes”. The historical usages and the recent advancement of new drugs in controlling possible therapeutical targets have been highlighted, in order to evaluate the evolution of knowledge in this sensitive area. It has recently been shown that the metabolic responses to stimuli (i.e., hyperglycemia) involve an integrated network of signaling pathways, in order to define the exact responses. Certain new drugs have been experimentally tested—or suggested and proposed—for their ability to modulate the possible biochemical therapeutical targets for the downregulation of retinopathy, nephropathy, neuropathy, heart disease, angiogenesis, oxidative stress, and cellular death. The aim of this study was to critically and didactically evaluate the exact steps of these signaling pathways and hence mark the indicated sites for the actions of such drugs and their possible consequences. This review will emphasize, besides others, the therapeutical targets for controlling the signaling pathways, when aimed at the downregulation of ROS generation, oxidative stress, and, consequently, cellular death—with all of these conditions being a problem in diabetes.

Objective: To evaluate inflammatory, oxidizing, and reducing responses during the progression of type 1 diabetes mellitus (T1DM) in patients without chronic complications. Subjects and methods: Plasma antioxidant status, reactive oxygen species (ROS), and interleukin-6 (IL-6) were measured in 42 patients with T1DM and in 24 healthy subjects. Results: Significant increases were detected in the median values of ROS and IL-6 in patients with T1DM compared with healthy subjects (ROS ~ 4,836 vs. 2,036 RLU/min, respectively; P < .05: IL-6 ~ 14.2 vs. 9.7 pg/mL, respectively; P = .002). No significant between-group differences (P > 0.05) were observed in oxidizing responses or in IL-6 concentrations when diabetic patients were grouped according to time after diagnosis (0 -10, 10 -20 and > 20 years). Plasma antioxidant responses were similar in patients with T1DM and in healthy subjects. Conclusions: Our results demonstrate that oxidizing and inflammatory responses are increased at the onset of T1DM, but remain unchanged during disease progression. These findings suggest that functional changes involved in diabetic complications may commence in the first years after diagnosis. Arq Bras Endocrinol Metab.2012;56(7):441-8 Keywords Type 1 diabetes; disease progression; oxidative stress; plasma antioxidant status RESUMO Objetivo: Avaliar as respostas inflamatória, oxidativa e redutora na progressão do diabetes melito tipo 1 (DM1) em pacientes sem complicações crônicas. Sujeitos e métodos: Capacidade antioxidante do plasma, espécies reativas de oxigênio (ROS) e interleucina-6 (IL-6) foram avaliadas em 42 pacientes com DM1 e 24 indivíduos saudáveis. Resultados: Aumentos significativos foram detectados nas medianas de ROS e IL-6 em pacientes com DM1 comparados com indiví-duos saudáveis (ROS ~ 4.836 vs. 2.036 RLU/min, respectivamente, P < 0,05: IL-6 ~ 14,2 vs. 9,7 pg/ mL, respectivamente, P = 0,002). Diferenças não significativas (P > 0,05) foram observadas na resposta oxidante e IL-6 quando os diabéticos foram agrupados de acordo com o tempo após o diagnóstico (0-10, 10-20 e > 20 anos). A resposta antioxidante do plasma foi semelhante em pacientes com DM1 e em indivíduos saudáveis. Conclusões: Nossos resultados demonstram que as respostas oxidante e inflamatória estão aumentadas desde o início do DM1, mas mantêm-se inalteradas durante a progressão da doença, sugerindo que as mudanças funcionais envolvidas nas complicações diabéticas podem começar nos primeiros anos após o diagnóstico. Arq Bras Endocrinol Metab. 2012;56(7):441-8 Descritores Diabetes tipo 1; progressão da doença; estresse oxidativo; capacidade oxidante do plasma

Malondialdehyde (MDA), an end product of lipid peroxidation and biomarker for oxidative stress, and its soluble receptor (sRAGE) were evaluated in 42 patients with type 1 diabetes mellitus, but without chronic complications, during the early years after diagnosis (0-10 years) and through the further progression of the disease (10-20 and > 20 years after diagnosis). Clinical and biochemical parameters of the cohort of diabetic patients were compared with those determined in 24 healthy individuals. The median levels of MDA in plasma were similar in type 1 diabetes patients and in healthy subjects. In contrast, statistically significant increases were detected in the median values of sRAGE in patients with type 1 diabetes compared with healthy subjects (2423.75 versus 1472.75 pg/ml; p=0.001, Mann-Whitney test). However, no significant between-group differences (p>0.05) were observed in levels of sRAGE when diabetic patients were grouped according to time elapsed after diagnosis. It is concluded that increased plasma levels of sRAGE in type 1 diabetes may provide protection against cell damage and may be sufficient to eliminate excessive circulating MDA during early years after disease onset.

Cancer is associated with immunodeficiency, while allergies result from immune system hyperactivity mediated by cytokines and immunoglobulins. The purpose of this study was to determine the relationship between immune environment of specific cancers and allergies, emphasizing cytokines related to Th1 and Th2 responses associated with IgE. 80 adults were distributed into two groups: control (n = 20) and cancer (n = 60), distributed in three subgroups (n = 20), head and neck, stomach, and prostate cancers. This study compared Th1 (IL-2) and Th2 (IL-4) parameters, anti-inflammatory, pro-inflammatory, or regulatory profile regarding both IgE levels and reported allergies, by means of clinical manifestations and IgE, IL-1β, IL-2, IL-4, IL-17, and TGF-β serum concentration. Clinically allergies were observed in 50% of the control group and in 20% of the cancer group (p = 0.009). IL-2 cytokine and TGF-β concentrations were higher in the patients with cancer as compared to the control (p < 0.005). However, there were IL-4, IL-17, and IL-1β decreases in the patients with cancer (p < 0.05). No correlation was observed between the cytokines studied and IgE and clinically proven allergies in both investigated groups. There was an inverse association between cancer and clinical allergy manifestations. In head and neck, stomach, and prostate cancers, an immunosuppressive serum tumor environment was predominant. There was no difference in cytokines related to Th1 and Th2 parameters in relation to IgE. No correlation was found between clinically proved allergies and immunity markers related to the same allergens.