Low frataxin mRNA expression is associated with inflammation and oxidative stress in patients with type 2 diabetes

BACKGROUND

The mitochondrial protein frataxin is involved in iron metabolism, as well as regulation of oxidative stress. To elucidate the association of frataxin with the pathophysiology of diabetes, we evaluated the mRNA levels of frataxin in leukocytes of patients with type 2 diabetes (T2D). In addition, we investigated the relation between frataxin mRNA levels, inflammatory cytokines, and oxidative stress biomarkers.

METHODS

A study including 150 subjects (115 patients with T2D and 35 healthy subjects) was performed to evaluate the frataxin mRNA levels in leukocytes. We assessed the relation between frataxin and interleukin (IL)-6, IL-1, tumour necrosis factor-alpha (TNF-α), total oxidation status (TOS), total antioxidant capacity (TAC), and serum iron.

RESULTS

The frataxin mRNA levels in the T2D group were significantly lower than those in healthy subjects. It was also demonstrated that T2D patients with frataxin mRNA levels in the lowest quartile had significantly elevated levels of serum iron, TOS, and inflammatory cytokines, such as TNF-α, IL-1, and IL-6, while TAC levels were significantly lower in this quartile when compared with the upper quartile.

CONCLUSIONS

Our findings showed that T2D patients with low frataxin mRNA levels showed a high degree of inflammation and oxidative stress. It is speculated that frataxin deficiency in T2D patients can contribute to the imbalance in mitochondrial iron homeostasis leading to the acceleration of oxidative stress and inflammation.

Reference limits of the urinary gamma-glutamyltransferase in a healthy population and effects of short-term storage on the enzyme activity

BACKGROUND

Gamma-glutamyltransferase (GGT) is present mainly in proximal renal tubule, and urinary GGT is an indicator of tubular damage since it may show renal changes before they are identified by using conventional measurements. Therefore, it is of interest to establish the reference limits of urinary GGT for a healthy population, as well as to investigate the stability of GGT in urine samples stored at 4 °C and -20 °C.

METHODS

GGT was assessed in urine samples from 127 healthy patients by use of a reference method based on the 5-Amino-2-Nitrobenzoate formation. Stability of GGT was evaluated in 10 urine samples stored at temperatures of 4 °C and -20 °C for a period up to 4 weeks.

RESULTS

Urinary GGT values for healthy volunteers were 14 U/g creatinine for the lower reference limit and 79 U/g creatinine for the upper reference limit. Urinary GGT values were approximately 56% lower in samples stored at -20 °C than fresh samples, while samples stored at 4 °C presented a decrease of 11% in GGT values compared to fresh samples.

CONCLUSIONS

Reference limits for urinary GGT in healthy subjects were 14 to 79 U/g creatinine, and it is recommended to measure urinary GGT in fresh specimens.

Urinary inflammatory cytokines as indicators of kidney damage in type 2 diabetic patients

BACKGROUND

The aim of this study was to investigate whether urinary levels of interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) are altered in normoalbuminuric patients with type 2 diabetes mellitus (T2DM), and whether these cytokines are able to identify diabetic kidney disease (DKD) among these patients.

METHODS

This study included 125 T2DM patients classified into 3 groups according to urinary albumin/creatinine ratio (uACR): uACR <10mg/g creatinine, uACR 10-30mg/g creatinine and uACR >30mg/g creatinine. Urinary inflammatory cytokines were measured.

RESULTS

The urinary IL-6 concentrations increased from uACR <10 (97.2±26.4pg/ml) to uACR 10-30 (113.6±28.0pg/ml) and to uACR >30mg/g creatinine (163.5±25.6pg/ml) (P<0.05 and P<0.001, respectively) patients. The urinary IL-10 concentrations decreased in these uACR ranges [100.0 (58.0-141.0) pg/ml vs. 62.0 (54.5-71.5) pg/ml vs. 42.0 (32.0-48.0) pg/ml] (P<0.05 and P<0.001, respectively). All urinary cytokines demonstrated good ability to identify DKD (areas under curves >0.9).

CONCLUSIONS

Urinary inflammatory cytokines, especially IL-6 and IL-10, may assist in the identification of DKD in T2DM patients, even in the absence of micro- and macroalbuminuria.

Urinary kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin as indicators of tubular damage in normoalbuminuric patients with type 2 diabetes

OBJECTIVES

Renal dysfunction has been reported in normoalbuminuric patients, demonstrating the necessity to improve the diagnostic and prognostic tools for diabetic kidney disease (DKD) investigation. Therefore, the aim of this study was to investigate whether the urinary levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are increased in type 2 diabetes mellitus (DM) patients with normal or mildly increased albuminuria.

DESIGN AND METHODS

In this study, 117 type 2 DM patients classified into three groups according to urinary albumin/creatinine ratio (uACR): uACR<10mg/g creatinine, uACR 10-30mg/g creatinine and uACR>30mg/g creatinine were enrolled. Urinary concentrations of KIM-1 (uKIM-1) and NGAL (uNGAL) were measured.

RESULTS

uKIM-1 levels increased progressively from uACR<10mg/g creatinine (69.0±20.8pg/ml) to uACR 10-30mg/g creatinine (106.1±41.2pg/ml) and to uACR>30mg/g creatinine (166.0±31.9pg/ml) (P<0.001). In addition, uNGAL levels increased progressively from uACR<10mg/g creatinine (29.5±8.8ng/ml) to uACR 10-30mg/g creatinine (51.7±10.9ng/ml) and to uACR>30mg/g creatinine (71.0±9.6ng/ml) (P<0.001) patients. Similarly, both uKIM-1 and uNGAL adjusted by urinary creatinine were increased in patients with uACR 10-30mg/g creatinine. Significant and positive correlations were observed between uACR, uKIM-1 and uNGAL.

CONCLUSIONS

uKIM-1 and uNGAL were increased in type 2 DM patients with normal or mildly increased albuminuria, which indicates that tubular and glomerular injuries may be occurring even at the earliest stage of DKD.

Oxidative DNA damage is associated with inflammatory response, insulin resistance and microvascular complications in type 2 diabetes

Urinary markers of nucleic acid oxidation may be useful biomarkers in diabetes. It has been demonstrated that T2DM patients have an increased level of oxidative DNA damage; however, it is unclear whether increased DNA damage may be related to a greater degree of inflammation and insulin resistance. Thus, the aim of this present study was to investigate the relation of the impact of oxidative DNA damage, assessed by urinary 8-OHdG, on the levels of inflammatory cytokines, as well as insulin resistance. In addition, we also investigated the diagnostic ability of urinary 8-OHdG in the identification of microvascular complications in T2DM.A case-control study, enrolling 22 healthy controls and 54 subjects with T2DM, was performed to evaluate the relation between oxidative DNA damage and interleukin-6 (IL-6), IL-1,tumor necrosis factor-alpha (TNF-α), IL-10, and Homeostasis Model Assessment (HOMA-IR) index. T2DM patients presented higher urinary 8-OHdG, IL-6, IL-1, TNF-α levels and HOMA-IR, and lower IL-10 levels than control subjects. Moreover, urinary 8-OHdG levels were significantly higher in the group T2DM with microvascular complications when compared to the without complications. The areas under the curve for urinary 8-OHdG and urinary albumin were, respectively, 0.836 (P<0.001) and 0.786 (P=0.002). Thus, urinary 8-OHdG has a slightly higher ability to discriminate microvascular complications in T2DM compared with urinary albumin. It was also demonstrated that T2DM patients with higher median of urinary 8-OHdG had significantly elevated levels of IL-6, TNF-α and HOMA-IR, and decreased IL-10 levels. Our findings showed that T2DM patients with higher urinary 8-OHdG levels showed a greater inflammatory degree and higher insulin resistance. It is possible to speculate that T2DM patients present a cascade of events as increasing metabolic abnormalities such as insulin resistance and inflammatory activation, as well as increased ROS generation factors that may contribute directly to greater oxidative DNA damage.

Oxidative stress in dogs with multicentric lymphoma: Effect of chemotherapy on oxidative and antioxidant biomarkers

INTRODUCTION

Lymphoma is one of the most common types of cancer in dogs, characterized by the proliferation of lymphoid cells. The treatment of this type of cancer is usually based on drugs with high toxicity, which can cause severe side effects.

OBJECTIVES

Therefore, the aim of this study was to measure the levels of advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS), and ferric reducing antioxidant power (FRAP) in dogs with multicentric lymphoma before and after chemotherapy.

METHODS

For this purpose, serum samples of 25 dogs diagnosed with multicentric lymphoma and 15 healthy dogs were used. The animals were exposed to CHOP chemotherapy (cyclophosphamide, vincristine, doxorubicin, and prednisone) and serum samples were collected 5 weeks after treatment.

RESULTS

High levels of TBARS, AOPP, and FRAP were observed in sera of dogs with multicentric lymphoma when compared to healthy dogs (P < 0.01), and even higher levels (TBARS and AOPP) were found after chemotherapy i.e. treatment exacerbated the oxidative stress levels. On the other hand, FRAP levels did not differ statistically between animals with lymphoma before and after treatment (P > 0.05). Exacerbated oxidative stress was observed in dogs with multicentric lymphoma Group II (Stage IV-V: involvement of lymph nodes and organs) compared to those in Group I (Stage I-III: only affected lymph nodes) of the disease, as well as the dogs with clinical signs and T immunophenotype. Another important result was observed after chemotherapy, where FRAP levels were higher in dogs that showed complete disease remission compared to animals with progressive disease.

CONCLUSIONS

Therefore, dogs with lymphoma showed protein oxidation and lipid peroxidation, as well as increased total antioxidants before and after chemotherapy compared to the control group.