Glycolytic lactate in diabetic kidney disease.

Lactate elevation is a well-characterized biomarker of mitochondrial dysfunction, but its role in diabetic kidney disease (DKD) is not well defined. Urine lactate was measured in patients with type 2 diabetes (T2D) in 3 cohorts (HUNT3, SMART2D, CRIC). Urine and plasma lactate were measured during euglycemic and hyperglycemic clamps in participants with type 1 diabetes (T1D). Patients in the HUNT3 cohort with DKD had elevated urine lactate levels compared with age- and sex-matched controls. In patients in the SMART2D and CRIC cohorts, the third tertile of urine lactate/creatinine was associated with more rapid estimated glomerular filtration rate decline, relative to first tertile. Patients with T1D demonstrated a strong association between glucose and lactate in both plasma and urine. Glucose-stimulated lactate likely derives in part from proximal tubular cells, since lactate production was attenuated with sodium-glucose cotransporter-2 (SGLT2) inhibition in kidney sections and in SGLT2-deficient mice. Several glycolytic genes were elevated in human diabetic proximal tubules. Lactate levels above 2.5 mM potently inhibited mitochondrial oxidative phosphorylation in human proximal tubule (HK2) cells. We conclude that increased lactate production under diabetic conditions can contribute to mitochondrial dysfunction and become a feed-forward component to DKD pathogenesis.

Pharmacological inhibition of the LIF/LIFR autocrine loop reveals vulnerability of ovarian cancer cells to ferroptosis.

Of all gynecologic cancers, epithelial-ovarian cancer (OCa) stands out with the highest mortality rates. Despite all efforts, 90% of individuals who receive standard surgical and cytotoxic therapy experience disease recurrence. The precise mechanism by which leukemia inhibitory factor (LIF) and its receptor (LIFR) contribute to the progression of OCa remains unknown. Analysis of cancer databases revealed that elevated expression of LIF or LIFR was associated with poor progression-free survival of OCa patients and a predictor of poor response to chemotherapy. Using multiple primary and established OCa cell lines or tissues that represent five subtypes of epithelial-OCa, we demonstrated that LIF/LIFR autocrine signaling is active in OCa. Moreover, treatment with LIFR inhibitor, EC359 significantly reduced OCa cell viability and cell survival with an IC50 ranging from 5-50 nM. Furthermore, EC359 diminished the stemness of OCa cells. Mechanistic studies using RNA-seq and rescue experiments unveiled that EC359 primarily induced ferroptosis by suppressing the glutathione antioxidant defense system. Using multiple in vitro, ex vivo and in vivo models including cell-based xenografts, patient-derived explants, organoids, and xenograft tumors, we demonstrated that EC359 dramatically reduced the growth and progression of OCa. Additionally, EC359 therapy considerably improved tumor immunogenicity by robust CD45+ leukocyte tumor infiltration and polarizing tumor-associated macrophages (TAMs) toward M1 phenotype while showing no impact on normal T-, B-, and other immune cells. Collectively, our findings indicate that the LIF/LIFR autocrine loop plays an essential role in OCa progression and that EC359 could be a promising therapeutic agent for OCa.

Female Protection Against Diabetic Kidney Disease Is Regulated by Kidney-Specific AMPK Activity.

Reduced kidney AMPK activity is associated with nutrient stress-induced chronic kidney disease (CKD) in male mice. In contrast, female mice resist nutrient stress-induced CKD. The role of kidney AMPK in sex-related organ protection against nutrient stress and metabolite changes was evaluated in diabetic kidney tubule-specific AMPKγ2KO (KTAMPKγ2ΚΟ) male and female mice. In wild-type (WT) males, diabetes increased albuminuria, urinary kidney injury molecule-1, hypertension, kidney p70S6K phosphorylation, and kidney matrix accumulation; these features were not exacerbated with KTAMPKγ2ΚΟ. Whereas WT females had protection against diabetes-induced kidney injury, KTAMPKγ2ΚΟ led to loss of female protection against kidney disease. The hormone 17ß-estradiol ameliorated high glucose-induced AMPK inactivation, p70S6K phosphorylation, and matrix protein accumulation in kidney tubule cells. The mechanism for female protection against diabetes-induced kidney injury is likely via an estrogen-AMPK pathway, as inhibition of AMPK led to loss of estrogen protection to glucose-induced mTORC1 activation and matrix production. RNA sequencing and metabolomic analysis identified a decrease in the degradation pathway of phenylalanine and tyrosine resulting in increased urinary phenylalanine and tyrosine levels in females. The metabolite levels correlated with loss of female protection. The findings provide new insights to explain evolutionary advantages to females during states of nutrient challenges.

A technology assisted precision ketogenic diet intervention for cardio-renal-metabolic health in overweight or obese adults: Protocol for a randomized controlled trial.

BACKGROUND: The obesity epidemic is a public health concern, as it is associated with a variety of chronic conditions. The ketogenic diet has drawn much scientific and public attention. However, implementation is challenging and its effect on cardio-renal-metabolic health is inconclusive. This study will assess the feasibility, acceptability, and preliminary efficacy of a technology-assisted ketogenic diet on cardio-renal-metabolic health. METHODS: This is a single center, 6-month, stratified, randomized controlled trial. A total of 60 overweight/obese adults (18+ years old) will be enrolled, including 20 without type 2 diabetes (T2D) and without chronic kidney disease (CKD); 20 with T2D, but without CKD; and 20 with early-stage CKD. Participants will be stratified based on health conditions and randomized into a ketogenic diet (n = 30) or a low-fat diet group (n = 30). Health education involving diet and physical activity will be delivered both digitally and in-person. Mobile and connected health technologies will be used to track lifestyle behaviors and health indicators, as well as provide weekly feedback. The primary outcome (weight) and the secondary outcomes (e.g., blood pressure, glycemic control, renal health) will be assessed with traditional measurements and metabolomics. DISCUSSION: Mobile and connected health technologies provide new opportunities to improve chronic condition management, health education attendance, planned lifestyle changes and engagement, and health outcomes. The advancement of bioinformatics technology offers the possibility to profile and analyze omics data which may advance our understanding of the underlying mechanisms of intervention effects on health outcomes at the molecular level for personalized and precision lifestyle interventions.

Urinary Proteomics Identifies Cathepsin D as a Biomarker of Rapid eGFR Decline in Type 1 Diabetes.

OBJECTIVE: Understanding mechanisms underlying rapid estimated glomerular filtration rate (eGFR) decline is important to predict and treat kidney disease in type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS: We performed a case-control study nested within four T1D cohorts to identify urinary proteins associated with rapid eGFR decline. Case and control subjects were categorized based on eGFR decline ≥3 and <1 mL/min/1.73 m2/year, respectively. We used targeted liquid chromatography-tandem mass spectrometry to measure 38 peptides from 20 proteins implicated in diabetic kidney disease. Significant proteins were investigated in complementary human cohorts and in mouse proximal tubular epithelial cell cultures. RESULTS: The cohort study included 1,270 participants followed a median 8 years. In the discovery set, only cathepsin D peptide and protein were significant on full adjustment for clinical and laboratory variables. In the validation set, associations of cathepsin D with eGFR decline were replicated in minimally adjusted models but lost significance with adjustment for albuminuria. In a meta-analysis with combination of discovery and validation sets, the odds ratio for the association of cathepsin D with rapid eGFR decline was 1.29 per SD (95% CI 1.07-1.55). In complementary human cohorts, urine cathepsin D was associated with tubulointerstitial injury and tubulointerstitial cathepsin D expression was associated with increased cortical interstitial fractional volume. In mouse proximal tubular epithelial cell cultures, advanced glycation end product-BSA increased cathepsin D activity and inflammatory and tubular injury markers, which were further increased with cathepsin D siRNA. CONCLUSIONS: Urine cathepsin D is associated with rapid eGFR decline in T1D and reflects kidney tubulointerstitial injury.

Temporal Telomere and DNA Damage Responses in the Space Radiation Environment.

Telomeres, repetitive terminal features of chromosomes essential for maintaining genome integrity, shorten with cell division, lifestyle factors and stresses, and environmental exposures, and so they provide a robust biomarker of health, aging, and age-related diseases. We assessed telomere length dynamics (changes over time) in three unrelated astronauts before, during, and after 1-year or 6-month missions aboard the International Space Station (ISS). Similar to our results for National Aeronautics and Space Administration's (NASA's) One-Year Mission twin astronaut (Garrett-Bakelman et al., 2019), significantly longer telomeres were observed during spaceflight for two 6-month mission astronauts. Furthermore, telomere length shortened rapidly after return to Earth for all three crewmembers and, overall, telomere length tended to be shorter after spaceflight than before spaceflight. Consistent with chronic exposure to the space radiation environment, signatures of persistent DNA damage responses were also detected, including mitochondrial and oxidative stress, inflammation, and telomeric and chromosomal aberrations, which together provide potential mechanistic insight into spaceflight-specific telomere elongation.

Nephrogenic Systemic Fibrosis Is Mediated by Myeloid C-C Chemokine Receptor 2.

Gadolinium-based contrast agents are implicated in several pathologic abnormalities (long-term retention in vital organs such as the skin and the brain) and are the cause of a sometimes fatal condition in patients, nephrogenic systemic fibrosis. Bone marrow-derived fibrocytes and the monocyte chemoattractant protein-1 inflammatory pathway have been implicated as mediators of the adverse effects induced by gadolinium-based contrast agents. Mechanistic studies are scant; therefore, a mouse model of nephrogenic systemic fibrosis was established. Dermal cellularity was increased in contrast-treated green fluorescent protein (GFP) chimeric mice. GFP in the skin and fibrosis were increased in the contrast-treated chimeric animals. Monocyte chemoattractant protein-1 and C-C chemokine receptor 2 were increased in the tissues from contrast-treated mice. C-C chemokine receptor 2-deficient recipients of GFP-expressing marrow had an abrogation of gadolinium-induced pathology and displayed less GFP-positive cells in the skin. Wild-type animals that received C-C chemokine receptor 2-deficient bone marrow had a complete abrogation of dermal pathology. That GFP levels and expression increase in the skin, in tandem with a fibrocyte marker, supports the blood-borne circulating fibrocyte hypothesis of the disease. As of now, fibrocyte trafficking has yet to be demonstrated. Importantly, our data demonstrate that the monocyte chemoattractant protein-1/C-C chemokine receptor 2 axis plays a critical role in the pathogenesis of nephrogenic systemic fibrosis.

Pathophysiology of gadolinium-associated systemic fibrosis.

Systemic fibrosis from gadolinium-based magnetic resonance imaging contrast is a scourge for the afflicted. Although gadolinium-associated systemic fibrosis is a rare condition, the threat of litigation has vastly altered clinical practice. Most theories concerning the etiology of the fibrosis are grounded in case reports rather than experiment. This has led to the widely accepted conjecture that the relative affinity of certain contrast agents for the gadolinium ion inversely correlates with the risk of succumbing to the disease. How gadolinium-containing contrast agents trigger widespread and site-specific systemic fibrosis and how chronicity is maintained are largely unknown. This review highlights experimentally-derived information from our laboratory and others that pertain to our understanding of the pathophysiology of gadolinium-associated systemic fibrosis.

Centrality of bone marrow in the severity of gadolinium-based contrast-induced systemic fibrosis.

Systemic fibrosis can be induced in humans with gadolinium-based contrast, and cumulative doses correlate with severity. Bone marrow-derived fibrocytes accumulate in the dermis. Whether target organs liberate chemokines to recruit these fibrocytes or whether fibrocytes are stimulated to home to the affected tissue is unknown. Transgenic (tagged) donor rats were treated with gadolinium-based contrast. Bone marrow was obtained from diseased animals and age-matched controls. Rats with subtotal nephrectomies were lethally irradiated and underwent salvage transplantation with either the contrast-naïve or contrast-exposed bone marrow. Groups were randomly assigned to control or contrast treatment. Contrast treatment led to dermal fibrosis, and this was exacerbated in recipients of contrast-exposed marrow. Fibronectin, C-C chemokine receptors (CCRs)2 and 7, and oxidative stress were all increased in skin from contrast-treated animals-all parameters more severe in recipients of contrast-treated animals. The respective ligands, monocyte chemoattractant protein and C-C motif ligand 19, were both elevated in skin from contrast-treated animals. Coadministration of gadolinium-based contrast and a CCR2 inhibitor reduced the severity of skin disease as well as dermal cellularity. The functional role of chemokines in the effects of gadolinium-based contrast was further confirmed in in situ coculture studies using neutralizing CCR2 antibodies. These data implicate dermal liberation of specific chemokines in the recruitment of circulating bone marrow-derived cells. The disease is augmented by bone marrow exposure to contrast, which explains why multiple exposures correlate with severity.-Drel, V. R., Tan, C., Barnes, J. L., Gorin, Y., Lee, D.-Y., Wagner, B. Centrality of bone marrow in the severity of gadolinium-based contrast-induced systemic fibrosis.

12/15-Lipoxygenase inhibition counteracts MAPK phosphorylation in mouse and cell culture models of diabetic peripheral neuropathy.

BACKGROUND: Increased mitogen-activated protein kinase (MAPK) phosphorylation has been detected in peripheral nerve of human subjects and animal models with diabetes as well as high-glucose exposed human Schwann cells, and have been implicated in diabetic peripheral neuropathy. In our recent studies, leukocytetype 12/15-lipoxygenase inhibition or gene deficiency alleviated large and small nerve fiber dysfunction, but not intraepidermal nerve fiber loss in streptozotocin-diabetic mice. METHODS: To address a mechanism we evaluated the potential for pharmacological 12/15-lipoxygenase inhibition to counteract excessive MAPK phosphorylation in mouse and cell culture models of diabetic neuropathy. C57Bl6/J mice were made diabetic with streptozotocin and maintained with or without the 12/15-lipoxygenase inhibitor cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC). Human Schwann cells were cultured in 5.5 mM or 30 mM glucose with or without CDC. RESULTS: 12(S) HETE concentrations (ELISA), as well as 12/15-lipoxygenase expression and p38 MAPK, ERK, and SAPK/JNK phosphorylation (all by Western blot analysis) were increased in the peripheral nerve and spinal cord of diabetic mice as well as in high glucose-exposed human Schwann cells. CDC counteracted diabetes-induced increase in 12(S)HETE concentrations (a measure of 12/15-lipoxygenase activity), but not 12/15-lipoxygenase overexpression, in sciatic nerve and spinal cord. The inhibitor blunted excessive p38 MAPK and ERK, but not SAPK/ JNK, phosphorylation in sciatic nerve and high glucose exposed human Schwann cells, but did not affect MAPK, ERK, and SAPK/JNK phosphorylation in spinal cord. CONCLUSION: 12/15-lipoxygenase inhibition counteracts diabetes related MAPK phosphorylation in mouse and cell culture models of diabetic neuropathy and implies that 12/15-lipoxygenase inhibitors may be an effective treatment for diabetic peripheral neuropathy.

Na+/H+-exchanger-1 inhibition counteracts diabetic cataract formation and retinal oxidative-nitrative stress and apoptosis.

The Na⁺-H⁺-exchanger-1 (NHE-1) controls intracellular pH and glycolytic enzyme activities, and its expression and activity are increased by diabetes and high glucose. NHE-1-dependent upregulation of the upper part of glycolysis, under conditions of inhibition (lens) or insufficient activation (retina) of glyceraldehyde 3-phosphate dehydrogenase, underlies diversion of the excessive glycolytic flux towards several pathways contributing to oxidative stress, a causative factor in diabetic cataractogenesis and retinopathy. This study evaluated the role for NHE-1 in diabetic cataract formation and retinal oxidative stress and apoptosis. Control and streptozotocin-diabetic rats were maintained with or without treatment with the NHE-1 inhibitor cariporide (Sanofi-Aventis, 10 mgkg-1d-1) for 3.5 months. In in vitro studies, bovine retinal pericytes and endothelial cells were cultured in 5 or 30 mM glucose, with or without 10 µM cariporide, for 7 days. A several-fold increase of the by-product of glycolysis, α-glycerophosphate, indicative of activation of the upper part of glycolysis, was present in both rat lens and retina at an early (1-month) stage of streptozotocin-diabetes. Cariporide did not affect diabetic hyperglycemia and counteracted lens oxidative-nitrative stress and p38 MAPK activation, without affecting glucose or sorbitol pathway intermediate accumulation. Cataract formation (indirect ophthalmoscopy and slit-lamp examination) was delayed, but not prevented. The number of TUNEL-positive cells per flat-mounted retina was increased 4.4-fold in diabetic rats (101 ± 17 vs. 23 ± 8 in controls , P<0.01), and this increase was attenuated by cariporide (45 ± 12, P<0.01). Nitrotyrosine and poly(ADP-ribose) fluorescence and percentage of TUNEL-positive cells were increased in pericytes and endothelial cells cultured in 30 mM glucose, and these changes were at least partially prevented by cariporide. In conclusion, NHE-1 contributes to diabetic cataract formation, and retinal oxidative-nitrative stress and apoptosis. The findings identify a new therapeutic target for diabetic ocular complications.

Poly(ADP-ribose)polymerase inhibition counteracts renal hypertrophy and multiple manifestations of peripheral neuropathy in diabetic Akita mice.

Poly(ADP-ribose) polymerase (PARP) activation has been implicated in the pathogenesis of diabetic complications, including nephropathy and peripheral neuropathy. This study aimed at evaluating the manifestations of both complications in diabetic Akita mice, a model of Type 1 (insulin-dependent) diabetes, and their amenability to treatment with the potent PARP inhibitor, 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de] anthracen-3-one (GPI-15427). Male non-diabetic C57Bl6/J and diabetic C57Bl/6-Ins2Akita/J (Akita) mice were maintained with or without treatment with GPI-15427, 30 mg/kg/day, for 4 weeks starting from 16 weeks of age. Sixteen week-old Akita mice displayed sensory nerve conduction velocity (SNCV) deficit, whereas the motor nerve conduction velocity (MNCV) tended to decrease, but the difference with controls did not achieve statistical significance. They also developed thermal and mechanical hypoalgesia and tactile allodynia. SNCV deficit, mechanical hypoalgesia, and tactile allodynia progressed with age whereas the severity of thermal hypoalgesia was similar in 16- and 20-week-old Akita mice. PARP inhibition alleviated, although it did not completely reverse, SNCV deficit, thermal and mechanical hypoalgesia and tactile allodynia. Sixteen-week-old Akita mice displayed MNCV deficit (41.3±2.5 vs. 51.0±1.2 m/sec in non-diabetic controls, P<0.01), axonal atrophy of myelinated fibers, kidney hypertrophy, and albuminuria. MNCV slowing, axonal atrophy, and kidney hypertrophy, but not albuminuria, were less severe in GPI-15427-treated age-matched Akita mice. Neuroprotective and nephroprotective effects of PARP inhibition were not due to alleviation of diabetic hyperglycemia, or peripheral nerve p38 mitogen-activated protein kinase activation. GPI-15427 did not affect any variables in control mice. In conclusion, the findings support an important role for PARP activation in diabetic peripheral neuropathy and kidney hypertrophy associated with Type 1 diabetes, and provide rationale for development and further studies of PARP inhibitors, for the prevention and treatment of these complications.

Baicalein alleviates diabetic peripheral neuropathy through inhibition of oxidative-nitrosative stress and p38 MAPK activation.

With the consideration of the multifactorial etiology of diabetic peripheral neuropathy, an ideal drug or drug combination should target at least several key pathogenetic mechanisms. The flavonoid baicalein (5,6,7-trihydroxyflavone) has been reported to counteract sorbitol accumulation, activation of 12/15-lipoxygenase, oxidative-nitrosative stress, inflammation, and impaired signaling in models of chronic disease. This study evaluated baicalein on diabetic peripheral neuropathy. Control and streptozotocin-diabetic C57Bl6/J mice were maintained with or without baicalein treatment (30 mg kg(-1) d(-1), i.p., for 4 weeks after 12 weeks without treatment). Neuropathy was evaluated by sciatic motor and hind-limb digital sensory nerve conduction velocities, thermal algesia (Hargreaves test), tactile response threshold (flexible von Frey filament test), and intraepidermal nerve fiber density (fluorescent immunohistochemistry with confocal microscopy). Sciatic nerve and spinal cord 12/15-lipoxygenase and total and phosphorylated p38 mitogen-activated protein kinase expression and nitrated protein levels were evaluated by Western blot analysis, 12(S)hydroxyeicosatetraenoic acid concentration (a measure of 12/15-lipoxygenase activity) by ELISA, and glucose and sorbitol pathway intermediate concentrations by enzymatic spectrofluorometric assays. Baicalein did not affect diabetic hyperglycemia, and alleviated nerve conduction deficit and small sensory nerve fiber dysfunction, but not intraepidermal nerve fiber loss. It counteracted diabetes-associated p38 mitogen-activated protein kinase phosphorylation, oxidative-nitrosative stress, and 12/15-lipoxygenase overexpression and activation, but not glucose or sorbitol pathway intermediate accumulation. In conclusion, baicalein targets several mechanisms implicated in diabetic peripheral neuropathy. The findings provide rationale for studying hydroxyflavones with an improved pharmacological profile as potential treatments for diabetic neuropathy and other diabetic complications.

PARP inhibition alleviates diabetes-induced systemic oxidative stress and neural tissue 4-hydroxynonenal adduct accumulation: correlation with peripheral nerve function.

This study evaluated the role of poly(ADP-ribose) polymerase (PARP) in systemic oxidative stress and 4-hydoxynonenal adduct accumulation in diabetic peripheral neuropathy. Control and streptozotocin-diabetic rats were maintained with or without treatment with the PARP inhibitor, 1,5-isoquinolinediol, 3 mg kg(-1) day(-1), for 10 weeks after an initial 2 weeks. Treatment efficacy was evaluated by poly(ADP-ribosyl)ated protein content in peripheral nerve and spinal cord (Western blot analysis) and dorsal root ganglion neurons and nonneuronal cells (fluorescence immunohistochemistry), as well as by indices of peripheral nerve function. Diabetic rats displayed increased urinary isoprostane and 8-hydroxy-2'-deoxyguanosine excretion (ELISA) and 4-hydroxynonenal adduct accumulation in endothelial and Schwann cells of the peripheral nerve, neurons, astrocytes, and oligodendrocytes of the spinal cord and neurons and glial cells of the dorsal root ganglia (double-label fluorescence immunohistochemistry), as well as motor and sensory nerve conduction velocity deficits, thermal hypoalgesia, and tactile allodynia. PARP inhibition counteracted diabetes-induced systemic oxidative stress and 4-hydroxynonenal adduct accumulation in peripheral nerve and spinal cord (Western blot analysis) and dorsal root ganglion neurons (perikarya, fluorescence immunohistochemistry), which correlated with improvement of large and small nerve fiber function. The findings reveal the important role of PARP activation in systemic oxidative stress and 4-hydroxynonenal adduct accumulation in diabetic peripheral neuropathy.

Different roles of 12/15-lipoxygenase in diabetic large and small fiber peripheral and autonomic neuropathies.

Up-regulation of 12/15-lipoxygenase, which converts arachidonic acid to 12(S)- and 15(S)-hydroxyeicosatetraenoic acids, causes impaired cell signaling, oxidative-nitrosative stress, and inflammation. This study evaluated the role for 12/15-lipoxygenase in diabetic large and small fiber peripheral and autonomic neuropathies. Control and streptozotocin-diabetic wild-type and 12/15-lipoxygenase-deficient mice were maintained for 14 to 16 weeks. 12/15-lipoxygenase gene deficiency did not affect weight gain or blood glucose concentrations. Diabetic wild-type mice displayed increased sciatic nerve 12/15-lipoxygenase and 12(S)-hydroxyeicosatetraenoic acid levels. 12/15-lipoxygenase deficiency prevented or alleviated diabetes-induced thermal hypoalgesia, tactile allodynia, motor and sensory nerve conduction velocity deficits, and reduction in tibial nerve myelinated fiber diameter, but not intraepidermal nerve fiber loss. The frequencies of superior mesenteric-celiac ganglion neuritic dystrophy, the hallmark of diabetic autonomic neuropathy in mouse prevertebral sympathetic ganglia, were increased 14.8-fold and 17.2-fold in diabetic wild-type and 12/15-lipoxygenase-deficient mice, respectively. In addition, both diabetic groups displayed small (<1%) numbers of degenerating sympathetic neurons. In conclusion, whereas 12/15-lipoxygenase up-regulation provides an important contribution to functional changes characteristic for both large and small fiber peripheral diabetic neuropathies and axonal atrophy of large myelinated fibers, its role in small sensory nerve fiber degeneration and neuritic dystrophy and neuronal degeneration characteristic for diabetic autonomic neuropathy is minor. This should be considered in the selection of endpoints for future clinical trials of 12/15-lipoxygenase inhibitors.

Protective effects of polyphenolics in red wine on diabetes associated oxidative/nitrative stress in streptozotocin-diabetic rats.

Increased accumulation of NT (3-nitrotyrosine) and PARylated [poly(ADP-ribosyl)ated] proteins in the tissues of diabetics are associated with diabetes complications (diabetes neuropathy, nephropathy and retinopathy). Red wine (its polyphenols are considered to be the main active components) can act as ROS (reactive oxygen species) scavengers, iron chelators and enzyme modulators. This study is novel in investigating the effect of red wine in preventing the accumulation of NT and PARylated proteins in the sciatic nerve, DRG (dorsal root ganglia), spinal cord, kidney and retina of diabetic animals. We have shown that during the experiment the body weight of control and diabetic groups of rats with consumption of red wine was significantly increased, by 52% and 19% accordingly. The significant increase in the content of NT in the sciatic nerve, DRG, spinal cord, kidney and retina, and PARylated proteins in the sciatic nerve, renal glomeruli and retinae of diabetic rats was partly or completely prevented by treatment with red wine. Red wine and its polyphenol preparations might be a promising option in the prevention and treatment of diabetic complications.

Role of 12/15-lipoxygenase in nitrosative stress and peripheral prediabetic and diabetic neuropathies.

This study evaluated the role of 12/15-lipoxygenase, which converts arachidonic acid to 12(S)- and 15(S)-hydroxyeicosatetraenoic acids, in nitrosative stress in the peripheral nervous system and peripheral prediabetic and diabetic neuropathies. The experiments were performed in C57BL6/J mice made diabetic with streptozotocin or fed a high-fat diet and in human Schwann cells cultured in 5.5 or 30 mM glucose. 12/15-Lipoxygenase overexpression and activation were present in sciatic nerve and spinal cord of diabetic and high-fat diet-fed mice, as well as in human Schwann cells cultured in high concentrations of D-, but not L-glucose. 12/15-Lipoxygenase inhibition by cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate (8 mg kg(-1) day(-1) sc, for 4 weeks after 12 weeks without treatment) alleviated the accumulation of nitrated proteins in the sciatic nerve and spinal cord, and large and small nerve fiber dysfunction, but not intraepidermal nerve fiber loss. 12/15-Lipoxygenase gene deficiency alleviated nitrosative stress and nerve conduction deficit, but not small sensory fiber neuropathy, in high-fat diet-fed mice. In conclusion, 12/15-lipoxygenase is implicated in nitrosative stress and peripheral neuropathy in mouse models of type 1 and early type 2 diabetes. Its presence in human Schwann cells and upregulation by high glucose suggest a potential involvement in human disease.

New therapeutic and biomarker discovery for peripheral diabetic neuropathy: PARP inhibitor, nitrotyrosine, and tumor necrosis factor-{alpha}.

This study evaluated poly(ADP-ribose) polymerase (PARP) inhibition as a new therapeutic approach for peripheral diabetic neuropathy using clinically relevant animal model and endpoints, and nitrotyrosine (NT), TNF-alpha, and nitrite/nitrate as potential biomarkers of the disease. Control and streptozotocin-diabetic rats were maintained with or without treatment with orally active PARP inhibitor 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]anthracen-3-one (GPI-15,427), 30 mg kg(-1) d(-1), for 10 wk after first 2 wk without treatment. Therapeutic efficacy was evaluated by poly(ADP-ribosyl)ated protein expression (Western blot analysis), motor and sensory nerve conduction velocities, and tibial nerve morphometry. Sciatic nerve and spinal cord NT, TNF-alpha, and nitrite/nitrate concentrations were measured by ELISA. NT localization in peripheral nervous system was evaluated by double-label fluorescent immunohistochemistry. A PARP inhibitor treatment counteracted diabetes-induced motor and sensory nerve conduction slowing, axonal atrophy of large myelinated fibers, and increase in sciatic nerve and spinal cord NT and TNF-alpha concentrations. Sciatic nerve NT and TNF-alpha concentrations inversely correlated with motor and sensory nerve conduction velocities and myelin thickness, whereas nitrite/nitrate concentrations were indistinguishable between control and diabetic groups. NT accumulation was identified in endothelial and Schwann cells of the peripheral nerve, neurons, astrocytes, and oligodendrocytes of the spinal cord, and neurons and glial cells of the dorsal root ganglia. The findings identify PARP as a compelling drug target for prevention and treatment of both functional and structural manifestations of peripheral diabetic neuropathy and provide rationale for detailed evaluation of NT and TNF-alpha as potential biomarkers of its presence, severity, and progression.

Poly(ADP-ribose) polymerase (PARP) inhibition counteracts multiple manifestations of kidney disease in long-term streptozotocin-diabetic rat model.

Evidence for the important role for poly(ADP-ribose) polymerase (PARP) in the pathogenesis of diabetic nephropathy is emerging. We previously reported that PARP inhibitors counteract early Type 1 diabetic nephropathy. This study evaluated the role for PARP in kidney disease in long-term Type 1 diabetes. Control and streptozotocin-diabetic rats were maintained with or without treatment with the PARP inhibitor 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de] anthracen-3-one (GPI-15,427, Eisai Inc.), 30mgkg(-1)d(-1), for 26 weeks after first 2 weeks without treatment. PARP activity in the renal cortex was assessed by Western blot analysis of poly(ADP-ribosyl)ated proteins. Urinary albumin, isoprostane, and 8-hydroxy-2'-deoxyguanosine excretion, and renal concentrations of transforming growth factor-beta(1), vascular endothelial growth factor, soluble intercellular adhesion molecule-1, fibronectin, and nitrotyrosine were evaluated by ELISA, and urinary creatinine and renal lipid peroxidation products by colorimetric assays. PARP inhibition counteracted diabetes-associated increase in renal cortex poly(ADP-ribosyl)ated protein level. Urinary albumin, isoprostane, and 8-hydroxy-2'-deoxyguanosine excretions and urinary albumin/creatinine ratio were increased in diabetic rats, and all these changes were at least partially prevented by GPI-15,427 treatment. PARP inhibition counteracted diabetes-induced renal transforming growth factor-beta(1), vascular endothelial growth factor, and fibronectin, but not soluble intercellular adhesion molecule-1 and nitrotyrosine, accumulations. Lipid peroxidation product concentrations were indistinguishable among control and diabetic rats maintained with or without GPI-15,427 treatment. In conclusion, PARP activation plays an important role in kidney disease in long-term diabetes. These findings provide rationale for development and further studies of PARP inhibitors and PARP inhibitor-containing combination therapies, for prevention and treatment of diabetic nephropathy.

Poly(Adenosine 5'-diphosphate-ribose) polymerase inhibition counteracts multiple manifestations of experimental type 1 diabetic nephropathy.

This study was aimed at evaluating the role for poly(ADP-ribose) polymerase (PARP) in early nephropathy associated with type 1 diabetes. Control and streptozotocin-diabetic rats were maintained with or without treatment with one of two structurally unrelated PARP inhibitors, 1,5-isoquinolinediol (ISO) and 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de] anthracen-3-one (GPI-15427), at 3 mg/kg(-1) x d(-1) ip and 30 mg/kg(-1) x d(-1), respectively, for 10 wk after the first 2 wk without treatment. PARP activity in the renal cortex was assessed by immunohistochemistry and Western blot analysis of poly(ADP-ribosyl)ated proteins. Variables of diabetic nephropathy in urine and renal cortex were evaluated by ELISA, Western blot analysis, immunohistochemistry, and colorimetry. Urinary albumin excretion was increased about 4-fold in diabetic rats, and this increase was prevented by ISO and GPI-15427. PARP inhibition counteracted diabetes-associated increase in poly(ADP-ribose) immunoreactivities in renal glomeruli and tubuli and poly(ADP-ribosyl)ated protein level. Renal concentrations of TGF-beta(1), vascular endothelial growth factor, endothelin-1, TNF-alpha, monocyte chemoattractant protein-1, lipid peroxidation products, and nitrotyrosine were increased in diabetic rats, and all these changes as well as an increase in urinary TNF-alpha excretion were completely or partially prevented by ISO and GPI-15427. PARP inhibition counteracted diabetes-induced up-regulation of endothelin (B) receptor, podocyte loss, accumulation of collagen-alpha1 (IY), periodic acid-Schiff-positive substances, fibronectin, and advanced glycation end-products in the renal cortex. In conclusion, PARP activation is implicated in multiple changes characteristic for early nephropathy associated with type 1 diabetes. These findings provide rationale for development and further studies of PARP inhibitors and PARP inhibitor-containing combination therapies.