Type 1 diabetes mellitus induces structural changes and molecular remodelling in the rat kidney

Roles of Matrix Metalloproteinases and Their Natural Inhibitors in Metabolism: Insights into Health and Disease

Matrix metalloproteinases (MMPs) are a family of zinc-activated peptidases that can be classified into six major classes, including gelatinases, collagenases, stromelysins, matrilysins, membrane type metalloproteinases, and other unclassified MMPs. The activity of MMPs is regulated by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). MMPs are involved in a wide range of biological processes, both in normal physiological conditions and pathological states. While some of these functions occur during development, others occur in postnatal life. Although the roles of several MMPs have been extensively studied in cancer and inflammation, their function in metabolism and metabolic diseases have only recently begun to be uncovered, particularly over the last two decades. This review aims to summarize the current knowledge regarding the metabolic roles of metalloproteinases in physiology, with a strong emphasis on adipose tissue homeostasis, and to highlight the consequences of impaired or exacerbated MMP actions in the development of metabolic disorders such as obesity, fatty liver disease, and type 2 diabetes.

hUCMSCs carrying exenatide prevent T1DM by improving intestinal microflora composition and islet tissue damage repair

BACKGROUND

Exenatide is a stable analogue of glucagon-like peptide 1 that can reduce postprandial hyperglycemia and has been utilized as adjunctive therapy for type 1 diabetes mellitus (T1DM). The human umbilical cord is a rich source of MSCs, and human umbilical cord mesenchymal stem cells (hUCMSCs) also show potential to enhance insulin secretion. Here, we aimed to explore the effects of hUCMSCs carrying exenatide in T1DM and further identify the possible mechanisms involved.

METHODS

hUCMSCs were isolated from human umbilical cord tissues, identified, and transduced with recombinant lentivirus carrying exenatide to obtain exenatide-carrying hUCMSCs (hUCMSCs@Ex-4).

RESULTS

The results showed that hUCMSCs@Ex-4 restored the blood glucose levels and body weight of NOD mice, and repressed immune cell infiltration and islet tissue changes. Additionally, in T1DM mice, treatment with hUCMSCs@Ex-4 reduced the blood glucose levels and promoted repair of islet tissue damage. Moreover, hUCMSCs@Ex-4 attenuated renal tissue lesions in T1DM mice. Applying bioinformatic analysis, the effects of hUCMSCs@Ex-4 were suggested to correlate with decreased abundance of pro-inflammatory intestinal bacteria and increased abundance of anti-inflammatory intestinal bacteria.

CONCLUSION

Overall, the study indicated that hUCMSCs carrying exenatide might improve beneficial intestinal microflora abundance and promote islet tissue damage repair, thereby alleviating T1DM.

Effects of Creatine Supplementation on Histopathological and Biochemical Parameters in the Kidney and Pancreas of Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) is a worldwide health concern, and projections state that cases will reach 578 million by 2030. Adjuvant therapies that can help the standard treatment and mitigate DM effects are necessary, especially those using nutritional supplements to improve glycemic control. Previous studies suggest creatine supplementation as a possible adjuvant therapy for DM, but they lack the evaluation of potential morphological parameters alterations and tissue injury caused by this compound. The present study aimed to elucidate clinical, histomorphometric, and histopathological consequences and the cellular oxidative alterations of creatine supplementation in streptozotocin (STZ)-induced type 1 DM rats. We could estimate whether the findings are due to DM or the supplementation from a factorial experimental design. Although creatine supplementation attenuated some biochemical parameters, the morphological analyses of pancreatic and renal tissues made clear that the supplementation did not improve the STZ-induced DM1 injuries. Moreover, creatine-supplemented non-diabetic animals were diagnosed with pancreatitis and showed renal tubular necrosis. Therefore, even in the absence of clinical symptoms and unaltered biochemical parameters, creatine supplementation as adjuvant therapy for DM should be carefully evaluated.

Nociceptin Increases Antioxidant Expression in the Kidney, Liver and Brain of Diabetic Rats

Simple Summary

Nociceptin (NC) is a small peptide implicated in the physiology of pain, learning and memory. Here we investigated the role of NC in the induction of antioxidants in the kidney, liver, and the brain of diabetic rats using morphological and biochemical methods. Normal and diabetic animals were treated with NC for 5 days. Catalase (CAT) was expressed in the kidney, liver, and the neurons of the brain. Although CAT was markedly (p < 0.05) lower in the tubules of the kidney of normal and diabetic animals after NC treatment, NC significantly (p < 0.001) increased the presence of CAT in the liver and brain of diabetic rats. Superoxide dismutase (SOD) was observed in kidney tubules, hepatocytes, and neurons of the brain. Treatment with NC markedly (p < 0.001) increased the level of SOD in hepatocytes and neurons of the brain. Glutathione reductase (GRED) was seen in the convoluted tubules of the kidney, hepatocytes and neurons of the brain. Treatment with NC markedly increased (p < 0.001) the expression of GRED in kidney tubules, hepatocytes and neurons of the brain. In conclusion, NC can help diabetic patients mitigate the effects of oxidative stress by its ability to induce endogenous antioxidants.

Abstract

Nociceptin (NC) consists of 17 amino acids (aa) and takes part in the processing of learning and memory. The role of NC in the induction of endogenous antioxidants in still unclear. We examined the effect of NC on the expression of endogenous antioxidants in kidney, liver, cerebral cortex (CC), and hippocampus after the onset of diabetes mellitus, using enzyme-linked immunosorbent assay and immunohistochemistry. Exogenous NC (aa chain 1–17; 10 µg/kg body weight) was given intraperitoneally to normal and diabetic rats for 5 days. Our results showed that catalase (CAT) is present in the proximal (PCT) and distal (DCT) convoluted tubules of kidney, hepatocytes, and neurons of CC and hippocampus. The expression of CAT was significantly (p < 0.05) reduced in the kidney of normal and diabetic rats after treatment with NC. However, NC markedly (p < 0.001) increased the expression CAT in the liver and neurons of CC of diabetic rats. Superoxide dismutase (SOD) is widely distributed in the PCT and DCT of kidney, hepatocytes, and neurons of CC and hippocampus. NC significantly (p < 0.001) increased the expression of SOD in hepatocytes and neurons of CC and the hippocampus but not in the kidney. Glutathione reductase (GRED) was observed in kidney tubules, hepatocytes and neurons of the brain. NC markedly increased (p < 0.001) the expression of GRED in PCT and DCT cells of the kidney and hepatocytes of liver and neurons of CC. In conclusion, NC is a strong inducer of CAT, SOD, and GRED expression in the kidney, liver and brain of diabetic rats.

Renoprotective effects of tropisetron through regulation of the TGF-β1, p53 and matrix metalloproteinases in streptozotocin-induced diabetic rats

Renal fibrosis is a major cause of renal failure in diabetic nephropathy. Tropisetron is an antagonist of the 5HT3 receptor that exhibits anti-fibrosis effects. The present research aimed to investigate the protected role of tropisetron against renal fibrosis of diabetic nephropathy and its molecular mechanisms. For this purpose, male Wistar rats were allocated into 5 groups of control, tropisetron, diabetes, tropisetron + diabetes, and glibenclamide + diabetes (n = 7). After induction of type 1 diabetes with a single injection of STZ, tropisetron (3 mg/kg) and glibenclamide (1 mg/kg) were given to the rats daily by intraperitoneal injection for 2 weeks. The obtained data revealed that the treatment of diabetic rats with tropisetron led to a significant decrease in the elevated blood glucose, serum cystatin c, and urinary total protein (UTP) level, indicating the improvement of the impaired kidney function. Moreover, the results of Masson's trichrome staining showed that fibrosis attenuated in the kidney of diabetic rats after tropisetron treatment. RT-PCR and Western blotting revealed that TGF-β1, the apoptotic mediator, and p53 were considerably declined in the kidney of diabetic rats in response to tropisetron treatment. Meanwhile, the expressions of matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-2 (MMP-2) were increased. These notable effects were equipotent with glibenclamide, as a standard drug, suggesting that tropisetron can alleviate renal fibrosis in diabetic nephropathy. Our data indicate that tropisetron could improve kidney function and attenuate renal fibrosis through regulation of TGF-β1, p53, and expression of extracellular matrix metalloproteinases.

The effect of tropisetron on oxidative stress, SIRT1, FOXO3a, and claudin-1 in the renal tissue of STZ-induced diabetic rats

Tropisetron is a 5-HT3 receptor antagonist that exerts protective effect against DN. The aim of this study was to investigate the possible molecular mechanisms associated with the renoprotective effects of tropisetron in STZ-induced diabetic rats. Animals were subdivided into 5 equal groups; control, tropisetron, diabetes, tropisetron + diabetes, and glibenclamide + diabetes (n = 7). For induction of type 1 diabetes, a single injection of STZ (55 mg/kg, i.p.) was administered to the animals. Diabetic rats were treated with tropisetron (3 mg/kg) and glibenclamide (1 mg/kg) for 2 weeks. According to the conducted analysis, diabetes led to renal dysfunction (reduction in glomerular filtration rate and urine urea and creatinine as well as elevation in plasma urea and creatinine) and abnormalities in antioxidant defense system (reduction in TAC and elevation in MDA), compared with the control group, which was prevented by tropisetron treatment. Reverse transcription-quantitative polymerase chain reaction and western blotting analysis demonstrated that SIRT1 gene expression decreased while FOXO3a and NF-κB gene expression as well as phosphorylated FOXO3a/total FOXO3a protein ratios and claudin-1 protein level increased in the kidney of diabetic rats compared with the control group. Herein, the results of this research showed that tropisetron treatment reversed these changes. Besides, all these changes were comparable with those produced by glibenclamide as a positive control. Hence, tropisetron ameliorated renal damage due to diabetic nephropathy possibly by suppressing oxidative stress and alteration of SIRT1, FOXO3a, and claudin-1 levels.

Influence of exercise training on diabetic kidney disease: A brief physiological approach

IMPACT STATEMENT

Diabetic kidney disease (DKD) is associated with increased mortality in diabetic patients and has a negative impact on public health. The identification of potential therapies that help the management of DKD can contribute to the improvement of health and quality of life of patients. Thus, this paper is timely and relevant because, in addition to presenting a concise review of the pathogenesis and major pathophysiological mechanisms of DKD, it addresses the most recent findings on the impact of exercise training on this disease. Thus, since non-pharmacological interventions have gained increasing attention in the fight against chronic diseases, this paper appears as an important tool to increase knowledge and stimulate innovative research on the impact of exercise on kidney disease.

Eyeing the Extracellular Matrix in Vascular Development and Microvascular Diseases and Bridging the Divide between Vascular Mechanics and Function

The extracellular matrix (ECM) is critical in all aspects of vascular development and health: supporting cell anchorage, providing structure, organization and mechanical stability, and serving as a sink for growth factors and sustained survival signals. Abnormal changes in ECM protein expression, organization, and/or properties, and the ensuing changes in vascular compliance affect vasodilator responses, microvascular pressure transmission, and collateral perfusion. The changes in microvascular compliance are independent factors initiating, driving, and/or exacerbating a plethora of microvascular diseases of the eye including diabetic retinopathy (DR) and vitreoretinopathy, retinopathy of prematurity (ROP), wet age-related macular degeneration (AMD), and neovascular glaucoma. Congruently, one of the major challenges with most vascular regenerative therapies utilizing localized growth factor, endothelial progenitor, or genetically engineered cell delivery, is the regeneration of blood vessels with physiological compliance properties. Interestingly, vascular cells sense physical forces, including the stiffness of their ECM, through mechanosensitive integrins, their associated proteins and the actomyosin cytoskeleton, which generates biochemical signals that culminate in a rapid expression of matricellular proteins such as cellular communication network 1 (CCN1) and CCN2 (aka connective tissue growth factor or CTGF). Loss or gain of function of these proteins alters genetic programs of cell growth, ECM biosynthesis, and intercellular signaling, that culminate in changes in cell behavior, polarization, and barrier function. In particular, the function of the matricellular protein CCN2/CTGF is critical during retinal vessel development and regeneration wherein new blood vessels form and invest a preformed avascular neural retina following putative gradients of matrix stiffness. These observations underscore the need for further in-depth characterization of the ECM-derived cues that dictate structural and functional properties of the microvasculature, along with the development of new therapeutic strategies addressing the ECM-dependent regulation of pathophysiological stiffening of blood vessels in ischemic retinopathies.

Urethral dysfunction and alterations of nitric oxide mechanisms in streptozotocin-induced diabetic rats with or without low-dose insulin treatment

AIMS

To establish an animal model of diabetes mellitus (DM) with moderately elevated blood glucose levels, and to examine the nitric oxide (NO) mechanism controlling urethral function in streptozotocin (STZ)-induced DM rats.

MAIN METHODS

Female Sprague-Dawley rats were used. DM was induced by intraperitoneal injection of STZ (65 mg/kg) and some of them received subcutaneous implantation of a low-dose insulin pellet. Voiding behavior was evaluated in metabolic cages. Isovolumetric cystometry and urethral perfusion pressure (UPP) were then evaluated under urethane anesthesia, during which L-arginine (100 mg/kg) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg/kg) were administered intravenously. In vitro urethral activity was also tested by organ bath muscle strip studies.

KEY FINDINGS

UPP changes and high-frequency oscillation (HFO) were significantly (P < 0.05) smaller in 8-weeks DM rats vs. normal control (NC) rats or insulin-treated DM rats, which showed reductions in urine overproduction and voided volume per micturition vs. untreated DM rats. UPP nadir was decreased by L-arginine in NC and insulin-treated DM groups, and decreased by L-NAME in all groups. Five of 6 untreated DM rats showed a detrusor-sphincter dyssynergia pattern after L-NAME. In in vitro studies, the relative ratio of L-NAME-induced reductions of urethral relaxation against pre-drug urethral relaxation was significantly smaller in DM vs. NC rats (P < 0.05).

SIGNIFICANCE

Low-dose insulin-treated DM rats would be a useful model for studying natural progression of DM-induced lower urinary tract dysfunction. The impaired NO-mediated urethral relaxation mechanisms play an important role in DM-induced urethral dysfunction, which could contribute to DM-induced inefficient voiding.

Preventive effect of exercise training on diabetic kidney disease in ovariectomized rats with type 1 diabetes

IMPACT STATEMENT

To date, no studies have been found evaluating the effects of physical exercise on renal function and structure changes in ovariectomized rats with type 1 diabetes. Therefore, this work emerges with an important tool for strengthening and expanding innovative research on exercise with potential for the prevention of renal diseases in ovariectomized diabetic rats, and future development of studies that seek to increase scientific knowledge about the beneficial effects of physical exercise on renal diseases in humans.

Arsenic exposure intensifies glycogen nephrosis in diabetic rats

It is known that either arsenic exposure or diabetes can impact renal function. However, it is unclear how these combined factors may influence kidney functions. Therefore, we evaluated morphological, functional, and oxidative parameters in the kidney of diabetic rats exposed to arsenic. Healthy male Wistar rats and streptozotocin-induced diabetic rats were exposed to 0 and 10 mg/L arsenate through drinking water for 40 days. Renal tissue was assessed using morphometry, mitosis and apoptosis markers, mineral proportion, oxidative stress markers, as well as the activity of antioxidant enzymes and membrane-bound adenosine triphosphatases. Arsenate intake altered glucose levels in healthy animals, but it did not reach hyperglycemic conditions. In diabetic animals, arsenate led to a remarkable increase of glycogen nephrosis in distal tubules. In these animals, additionally, the activity of catalase and glutathione S-transferase, besides the proportion of Fe, Cu, and K in renal tissue, was altered. Nevertheless, arsenate did not accumulate in the kidney and did not impact on other parameters previously altered by diabetes, including levels of malondialdehyde, Na, urea, creatinine, and apoptosis and mitosis markers. In conclusion, besides the intensification of glycogen nephrosis, the kidney was able to handle arsenate toxicity at this point, preventing arsenic deposition in the exposed groups and the impairment of renal function.