No abstract

Tubulointerstitial fibrosis (TIF) plays an important role in the progression of renal fibrosis in diabetic nephropathy (DN). Accumulating evidence supports a crucial inhibitory effect of dapagliflozin, a SGLT2 inhibitor, on TIF, but the underlying mechanisms remain largely unknown. This study aimed to shed light on the efficacy of dapagliflozin in reducing TIF as well as its possible impact on renal function. TIF in human kidney biopsies obtained from patients with DN was quantified by histopathological staining. In vitro , HK-2 cells were incubated in high glucose with dapagliflozin or fludarabine, and epithelial-mesenchymal transition (EMT) was determined. In vivo experiments were performed in streptozotocin (STZ)-induced type 1 diabetic mice treated with dapagliflozin by gavage for 16 weeks, after which specific functional characteristics and TIF were analyzed. In both DN patients and diabetic mice, fibronectin and Col IV, as well as STAT1 protein in the kidneys were increased as compared with controls. Dapagliflozin significantly decreased blood glucose, and renal STAT1 and TGF-β1 expression in mice. Furthermore, dapagliflozin improved renal function, and attenuated diabetes-induced TIF. In HK-2 cells, dapagliflozin, and fludarabine directly decreased aberrant STAT1 expression and reversed high glucose-induced downregulation of E-cadherin and α-SMA induction. Thus, the results demonstrate that dapagliflozin not only improves hyperglycemia but also slows down the progression of diabetes-associated renal TIF by improving hyperglycemia-induced activation of the STAT1/TGF-β1 pathway.

Epigallocatechin gallate (EGCG), the most abundant flavanoid in green tea, is currently being evaluated in the clinic due to its benefits in the treatment of amyloid disorders. Its anti-amyloidogenic effect has been attributed to direct interaction of the intact molecule with misfolded polypeptides. In addition, antioxidant activity is also involved in the anti-amyloidogenic role. The detailed molecular mechanism is still unclear and requires further investigation. In the present study, the kinetics of EGCG oxidation and the anti-amyloidogenic effect of the resultant oxidation substances have been examined. The results indicate that EGCG degrades in a medium at pH 8.0 with a half-life less than 2 h. By utilizing lysozyme as an in vitro model, the oxidized EGCG demonstrates a more potent anti-amyloidogenic capacity than the intact molecule, as shown by ThT and ANS fluorescence, TEM determination, and hemolytic assay. The oxidized EGCG also has a stronger disruptive effect on preformed fibrils than the native form. Ascorbic acid eliminates the disruptive role of native EGCG on the fibrils, suggesting that oxidation is a prerequisite in fibril disruption. The results of this work demonstrate that oxidized EGCG plays a more important role than the intact molecule in anti-amyloidogenic activity. These insights into the action of EGCG may provide a novel route to understand the anti-amyloidogenic activity of natural polyphenols.

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease involving both upper and lower motor neurons. The mechanism of motor neuron degeneration is still unknown. Although many studies have been performed on spinal motor neurons, few have been reported on brainstem and its motor nuclei. The aim of this study was to investigate oxidative stress and autophagic changes in the brainstem and representative motor nuclei of superoxide dismutase 1 (SOD1)-G93A mouse model of ALS. The expression levels of cluster of differentiation molecule 11b (CD11b), glial fibrillary acidic protein, glutamate-cysteine ligase catalytic subunit, heme oxygenase-1, NAD(P)H: quinone oxidoreductase 1, voltage-dependent anion-selective channel protein 1, Sequestosome 1/p62 (p62), microtubule-associated protein 1 light chain 3B (LC3), and SOD1 proteins in brainstem were examined by Western blot analysis. Immunohistochemistry and immunofluorescence were performed to identify the cellular localization of SOD1, p62, and LC3B, respectively. The results showed that there were progressive asctrocytic proliferation and microglial activation, induction of antioxidant proteins, and increased p62 and LC3II expression in brainstem of SOD1-G93A mice. Additionally, SOD1 and p62 accumulated in hypoglossal, facial, and red nuclei, but not in oculomotor nucleus. Furthermore, electron microscope showed increased autophagic vacuoles in affected brainstem motor nuclei. Our results indicate that brainstem share similar gliosis, oxidative stress, and autophagic changes as the spinal cord in SOD1-G93A mice. Thus, SOD1 accumulation in astrocytes and neurons, oxidative stress, and altered autophagy are involved in motor neuron degeneration in the brainstem, similar to the motor neurons in spinal cord. Therefore, therapeutic trials in the SOD1G93A mice need to target the brainstem in addition to the spinal cord.