Measurement of deoxyinosine adduct: Can it be a reliable tool to assess oxidative or nitrosative DNA damage?

Characterization of urinary biomarkers and their relevant mechanisms of zoledronate-induced nephrotoxicity using rats and HK-2 cells

The aim of this study was to identify biomarkers of zoledronate-induced nephrotoxicity and to further characterize the mechanisms underlying this process by analyzing urinary metabolites. Twenty-four rats were randomly divided into four groups containing four (two control groups) or eight rats (two zoledronate groups) per group. The rats were injected intravenously with saline or zoledronate (3 mg/kg) singly (single, 3 weeks) or repeatedly eight times (3 weeks/time, 24 weeks). Serum blood urea nitrogen, serum creatinine, creatinine clearance, and kidney injury observed by hematoxylin and eosin and immunohistochemical staining were changed only in the repeated zoledronate group (3 mg/kg, 3 weeks/time, 24 weeks). Urinary levels of S-adenosylmethionine, S-adenosylhomocysteine, l-cystathionine, l-γ-glutamylcysteine, and glutathione related to glutathione metabolism and fumaric acid and succinic acid related to the tricarboxylic acid cycle in the zoledronate-treated group (3 mg/kg, 3 weeks/time, 24 weeks) were significantly lower than those in the control group, suggesting that zoledronate may cause cellular oxidative stress. Besides, urinary levels of uracil and uridine related to pyrimidine metabolism also decreased after zoledronate treatment (3 mg/kg, 3 weeks/time, 24 weeks), while the levels of hypoxanthine related to purine metabolism, histamine related to histamine metabolism, and several amino acids were significantly increased. Moreover, zoledronate-induced enhanced oxidative stress and histamine overproduction were confirmed by reactive oxygen species (ROS) and histamine measurement in a human proximal tubular cell line. Taken together, zoledronate-induced nephrotoxicity may be attributed to it inducing perturbations in glutathione biosynthesis and the tricarboxylic acid cycle, further causing ROS overproduction, oxidative stress, and cellular inflammation, thereby leading to nephrotoxicity.

Effects of HIV on metabolic and biological pathways of CD4+ T lymphocytes

The effects of human immunodeficiency virus (HIV) on the metabolic and biological pathways of cluster of differentiation (CD)4⁺ T lymphocytes were investigated. A total of 150 patients with acquired immune deficiency syndrome (AIDS) and 50 healthy individuals who were admitted to hospital for physical examination during the period of June 2016 to January 2017, were selected as subjects in the present study. According to the virus load, 150 AIDS patients were divided into three groups: i) Viral load >10⁶ copies/ml (group A, n=39), ii) 10⁴ copies/ml < viral load <10⁵ copies/ml (group B, n=76), and iii) viral load <10⁴ copies/ml (group C, n=35). The relationship between viral loads in the three groups and CD4⁺ T lymphocyte counts was assessed. Active lymphocytes were isolated from T lymphocytes in the subjects, and the ratio of Th1 to Th2 was measured by flow cytometry. Effects of HIV on human T-lymphocyte differentiation were observed. Differences in T-lymphocyte metabolites were detected by proton nuclear magnetic resonance and their biological pathways analyzed. The results showed that CD4⁺ T-cell counts were decreased with the increase of the viral loads of patients. The viral loads of AIDS patients differentiated T lymphocytes. In other words, high viral loads accelerated the differentiation of T lymphocytes into Th1 cells. In the high HIV viral load group, the levels of glycerol phosphodiesterase, 7-dehydrocholesterol, p-hydroxyphenylacetic acid, cholesterol and deoxyuridine were increased, but the levels of 3-methoxytyramine, cytidine deaminase, deoxycorticosterone and 3-hydroxybutyric acid were decreased. The viral loads of AIDS patients are associated with CD4⁺ T-cell counts and the ratio of CD4⁺ T to CD8⁺ T cells. At the same time, HIV viral loads can affect the lipid biosynthesis of T-lymphocyte membranes, thus affecting the differentiation and proliferation of T lymphocytes and finally intervening its mediated immune responses.