Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study

The Common Single Cause of Chronic Multi-Hormonal Resistance in Oxidative Stress

In diseases with concomitant oxidative stress, chronic multi-hormonal resistances could be detected. The most conspicuous component of these resistances is insulin resistance, but also leptin, erythropoietin, acetylcholine, triiodothyronine and glucagon-like peptide-1 resistances also occur. On the other hand, in oxidative stress, abnormal tyrosines, for instance, meta- and ortho-tyrosine are also produced and incorporated into the proteins through the translational process. In case these modified proteins are components of the intracellular signalling pathways, a hormonal resistance may develop. The above-mentioned hormones, owning overlapping signalling pathways at the insulin receptor substrate, develop an abnormal tyrosine phosphorylation dependent chronic multi-hormonal resistance. A few weeks free of oxidative stress or the use of antioxidant therapy are required to provide a return from this resistance, which return may be further supported by the supplementation of physiological para-tyrosine and by the add-on therapy of a pharmacological dose of glucagon-like peptide-1 receptor agonist, which is able to bypass the critical insulin receptor substrate signalling.

Inflammatory markers S100A8/A9 and metabolic alteration for evaluating signs of early phase toxicity of anticancer agent treatment

Anticancer agents can cause various side effects, including tissue damages/inflammatory reactions. Drug-responsive biomarkers are essential for evaluating drug toxicity in disease processes. S100 calcium-binding proteins A8/A9 (S100A8/A9) are highly expressed in neutrophils and monocytes/macrophages accumulated at inflammatory sites and are known to be related to tissue damage/inflammation; however, their response to drug toxicity has not been reported. Herein, we investigated the effects of anticancer agents (doxorubicin, cisplatin, and docetaxel) on S100A8/A9 gene expression profiles in four representative tissues (heart, kidney, liver, and lung) in normal C57BL/6J mice. Both S100A8/A9 expression was transiently or time-dependently elevated in four tissues within 48 h after dosing of the three anticancer agents under toxicity-inducing conditions. S100A8/A9 patterns differed among agents and tissues. This result suggests that S100A8/A9 is useful for evaluating anticancer agent-induced tissue damage. Metabolomic analysis revealed that some metabolites showed temporal patterns similar to that of S100A8/A9 expression. The amounts of fumarate (doxorubicin-treated heart), tyrosine (cisplatin-treated kidney), acetylcarnosine (doxorubicin-treated liver), and 2-phosphoglycerate (docetaxel-treated lung) showed similar patterns to that of S100A8/A9 expression. Although these metabolites showed different behaviors between tissues and serum, they may be useful marker candidates for evaluating anticancer agent-induced tissue damage at an earlier stage after dosing.

Patient Stratification in Sepsis: Using Metabolomics to Detect Clinical Phenotypes, Sub-Phenotypes and Therapeutic Response

Infections are common and need minimal treatment; however, occasionally, due to inappropriate immune response, they can develop into a life-threatening condition known as sepsis. Sepsis is a global concern with high morbidity and mortality. There has been little advancement in the treatment of sepsis, outside of antibiotics and supportive measures. Some of the difficulty in identifying novel therapies is the heterogeneity of the condition. Metabolic phenotyping has great potential for gaining understanding of this heterogeneity and how the metabolic fingerprints of patients with sepsis differ based on survival, organ dysfunction, disease severity, type of infection, treatment or causative organism. Moreover, metabolomics offers potential for patient stratification as metabolic profiles obtained from analytical platforms can reflect human individuality and phenotypic variation. This article reviews the most relevant metabolomic studies in sepsis and aims to provide an overview of the metabolic derangements in sepsis and how metabolic phenotyping has been used to identify sub-groups of patients with this condition. Finally, we consider the new avenues that metabolomics could open, exploring novel phenotypes and untangling the heterogeneity of sepsis, by looking at advances made in the field with other -omics technologies.

Assessment of serum phenylalanine and tyrosine isomers in patients with ST-segment elevation vs non-ST-segment elevation myocardial infarction

Background

Under conditions of oxidative stress, hydroxyl radicals can oxidize phenylalanine (Phe) into various tyrosine (Tyr) isomers (meta‐, ortho‐, and para‐tyrosine; m‐, o‐, and p‐Tyr), depending on the location of the hydroxyl group on the oxidized benzyl ring. This study aimed to compare patients with ST‐segment elevation myocardial infarction (STEMI) and non‐STEMI (NSTEMI) and the serum levels of Phe and Tyr isomers at the aortic root and distal to the culprit lesion in both groups.

Methods

Forty‐four patients participated in the study: 23 with STEMI and 21 with NSTEMI. Arterial blood samples were taken from the aortic root through a guiding catheter and from the culprit vessel segment distal from the primary lesion with an aspiration catheter, during the percutaneous coronary intervention. Serum levels of Phe, p‐Tyr, m‐Tyr, and o‐Tyr were determined using reverse‐phase high‐performance liquid chromatography.

Results

Serum levels of Phe were significantly higher distal to the culprit lesion compared to the aortic root in patients with STEMI. Serum p‐Tyr/Phe and m‐Tyr/Phe concentration ratios were both lower distal to the culprit lesion than at the aortic root in patients with STEMI. There were no statistically significant differences with respect to changes in serum Phe and Tyr isomers distal to the culprit lesion compared to the aortic root in patients with NSTEMI.

Conclusion

Our data suggest that changes in serum levels of different Tyr isomers can mediate the effects of oxidative stress during myocardial infarction.

Non-Melanoma Skin Cancers: Biological and Clinical Features

Non-melanoma skin cancers (NMSCs) include basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and Merkel cell carcinoma (MCC). These neoplasms are highly diverse in their clinical presentation, as well as in their biological evolution. While the deregulation of the Hedgehog pathway is commonly observed in BCC, SCC and MCC are characterized by a strikingly elevated mutational and neoantigen burden. As result of our improved understanding of the biology of non-melanoma skin cancers, innovative treatment options including inhibitors of the Hedgehog pathway and immunotherapeutic agents have been recently investigated against these malignancies, leading to their approval by regulatory authorities. Herein, we review the most relevant biological and clinical features of NMSC, focusing on innovative treatment approaches.

Roles of the tyrosine isomers meta-tyrosine and ortho-tyrosine in oxidative stress

The damage to cellular components by reactive oxygen species, termed oxidative stress, both increases with age and likely contributes to age-related diseases including Alzheimer's disease, atherosclerosis, diabetes, and cataract formation. In the setting of oxidative stress, hydroxyl radicals can oxidize the benzyl ring of the amino acid phenylalanine, which then produces the abnormal tyrosine isomers meta-tyrosine or ortho-tyrosine. While elevations in m-tyrosine and o-tyrosine concentrations have been used as a biological marker of oxidative stress, there is emerging evidence from bacterial, plant, and mammalian studies demonstrating that these isomers, particularly m-tyrosine, directly produce adverse effects to cells and tissues. These new findings suggest that the abnormal tyrosine isomers could in fact represent mediators of the effects of oxidative stress. Consequently the accumulation of m- and o-tyrosine may disrupt cellular homeostasis and contribute to disease pathogenesis, and as result, effective defenses against oxidative stress can encompass not only the elimination of reactive oxygen species but also the metabolism and ultimately the removal of the abnormal tyrosine isomers from the cellular amino acid pool. Future research in this area is needed to clarify the biologic mechanisms by which the tyrosine isomers damage cells and disrupt the function of tissues and organs and to identify the metabolic pathways involved in removing the accumulated isomers after exposure to oxidative stress.

Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review

Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases.