4-Hydroxynonenal impairs miRNA maturation in heart failure via Dicer post-translational modification.

BACKGROUND AND AIMS: Developing novel therapies to battle the global public health burden of heart failure remains challenging. This study investigates the underlying mechanisms and potential treatment for 4-hydroxynonenal (4-HNE) deleterious effects in heart failure. METHODS: Biochemical, functional, and histochemical measurements were applied to identify 4-HNE adducts in rat and human failing hearts. In vitro studies were performed to validate 4-HNE targets. RESULTS: 4-HNE, a reactive aldehyde by-product of mitochondrial dysfunction in heart failure, covalently inhibits Dicer, an RNase III endonuclease essential for microRNA (miRNA) biogenesis. 4-HNE inhibition of Dicer impairs miRNA processing. Mechanistically, 4-HNE binds to recombinant human Dicer through an intermolecular interaction that disrupts both activity and stability of Dicer in a concentration- and time-dependent manner. Dithiothreitol neutralization of 4-HNE or replacing 4-HNE-targeted residues in Dicer prevents 4-HNE inhibition of Dicer in vitro. Interestingly, end-stage human failing hearts from three different heart failure aetiologies display defective 4-HNE clearance, decreased Dicer activity, and miRNA biogenesis impairment. Notably, boosting 4-HNE clearance through pharmacological re-activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) using Alda-1 or its improved orally bioavailable derivative AD-9308 restores Dicer activity. ALDH2 is a major enzyme responsible for 4-HNE removal. Importantly, this response is accompanied by improved miRNA maturation and cardiac function/remodelling in a pre-clinical model of heart failure. CONCLUSIONS: 4-HNE inhibition of Dicer directly impairs miRNA biogenesis in heart failure. Strikingly, decreasing cardiac 4-HNE levels through pharmacological ALDH2 activation is sufficient to re-establish Dicer activity and miRNA biogenesis; thereby representing potential treatment for patients with heart failure.

Wnt signaling is involved in crotalphine-induced analgesia in a rat model of neuropathic pain.

The aberrant activation of Wnt/ß-catenin and atypical Wnt/Ryk signaling pathways in the spinal cord is critical for the development and maintenance of neuropathic pain. Crotalphine is a structural analog to a peptide first identified in Crotalus durissus terrificus snake venom, which induces antinociception by activating kappa-opioid and CB2 cannabinoid receptors. Consistent with previous data, we showed that the protein levels of the canonical Wnt/ß-catenin and the atypical Wnt/Ryk signaling pathways are increased in neuropathic rats. Importantly, the administration of crotalphine downregulates these protein levels, including its downstream cascades, such as TCF4 from the canonical pathway and NR2B glutamatergic receptor and Ca2+-dependent signals, via the Ryk receptor. The CB2 receptor antagonist, AM630, abolished the crotalphine-induced atypical Wnt/Ryk signaling pathway activation. However, the selective CB2 agonist affects both canonical and non-canonical Wnt signaling in the spinal cord. Next, we showed that crotalphine blocked hypersensitivity and significantly decreased the concentration of IL-1ɑ, IL-1ß, IL-6, IL-10, IL-18, TNF-ɑ, MIP-1ɑ and MIP-2 induced by intrathecal injection of exogenous Wnt-3a agonist. Taken together, our findings show that crotalphine induces analgesia in a neuropathic pain model by down-regulating the canonical Wnt/ß-catenin and the atypical Wnt/Ryk signaling pathways and, consequently controlling neuroinflammation. This effect is, at least in part, mediated by CB2 receptor activation. These results open a perspective for new approaches that can be used to target Wnt signaling in the context of chronic pain. PERSPECTIVE: Our work identified that crotalphine-induced activation of CB2 receptors plays a critical role in the impairment of Wnt signaling during neuropathic pain. This work suggests that drugs with opioid/cannabinoid activity may be a useful strategy to target Wnt signaling in the context of chronic pain.

Formyl peptide receptors are involved in CTX-induced impairment of lymphocyte functions.

Crotoxin (CTX) is a neurotoxin that is isolated from the venom of Crotalus durissus terrificus, which displays immunomodulatory, anti-inflammatory, and anti-tumoral effects. Previous research has demonstrated that CTX promotes the adherence of leukocytes to the endothelial cells in blood microcirculation and the high endothelial venules of lymph nodes, which reduces the number of blood cells and lymphocytes. Studies have also shown that these effects are mediated by lipoxygenase-derived mediators. However, the exact lipoxygenase-derived eicosanoid involved in the CTX effect on lymphocytes is yet to be characterized. As CTX stimulates lipoxin-derived mediators from macrophages and lymphocyte effector functions could be modulated by activating formyl peptide receptors, we aimed to investigate whether these receptors were involved in CTX-induced redistribution and functions of lymphocytes in rats. We used male Wistar rats treated with CTX to demonstrate that Boc2 (butoxycarbonyl-Phe-Leu-Phe-Leu-Phe), an antagonist of formyl peptide receptors, prevented CTX-induced decrease in the number of circulating lymphocytes and increased the expression of the lymphocyte adhesion molecule LFA1. CTX reduced the T and B lymphocyte functions, such as lymphocyte proliferation in response to the mitogen Concanavalin A and antibody production in response to BSA immunization, respectively, which was prevented by the administration of Boc2. Importantly, mesenteric lymph node lymphocytes from CTX-treated rats showed an increased release of 15-epi-LXA4. These results indicate that formyl peptide receptors mediate CTX-induced redistribution of lymphocytes and that 15-epi-LXA4 is a key mediator of the immunosuppressive effects of CTX.

A human TRPV1 genetic variant within the channel gating domain regulates pain sensitivity in rodents.

Pain signals are relayed to the brain via a nociceptive system, and in rare cases, this nociceptive system contains genetic variants that can limit the pain response. Here, we questioned whether a human transient receptor potential vanilloid 1 (TRPV1) missense variant causes a resistance to noxious stimuli and, further, whether we could target this region with a cell-permeable peptide as a pain therapeutic. Initially using a computational approach, we identified a human K710N TRPV1 missense variant in an otherwise highly conserved region of mammalian TRPV1. After generating a TRPV1K710N-knockin mouse using CRISPR/Cas9, we discovered that the K710N variant reduced capsaicin-induced calcium influx in dorsal root ganglion neurons. The TRPV1K710N rodents also had less acute behavioral responses to noxious chemical stimuli and less hypersensitivity to nerve injury, while their response to noxious heat remained intact. Furthermore, blocking this K710 region in WT rodents using a cell-penetrating peptide limited acute behavioral responses to noxious stimuli and returned pain hypersensitivity induced by nerve injury to baseline levels. These findings identify K710 TRPV1 as a discrete site that is crucial for the control of nociception and provide insights into how to leverage rare genetic variants in humans to uncover fresh strategies for developing pain therapeutics.

Caspase-1 and Cathepsin B Inhibitors from Marine Invertebrates, Aiming at a Reduction in Neuroinflammation.

Neuroinflammation is a condition associated with several types of dementia, such as Alzheimer's disease (AD), mainly caused by an inflammatory response to amyloid peptides that induce microglial activation, with subsequent cytokine release. Neuronal caspase-1 from inflammasome and cathepsin B are key enzymes mediating neuroinflammation in AD, therefore, revealing new molecules to modulate these enzymes may be an interesting approach to treat neurodegenerative diseases. In this study, we searched for new caspase-1 and cathepsin B inhibitors from five species of Brazilian marine invertebrates (four cnidarians and one echinoderm). The results show that the extract of the box jellyfish Chiropsalmus quadrumanus inhibits caspase-1. This extract was fractionated, and the products monitored for their inhibitory activity, until the obtention of a pure molecule, which was identified as trigonelline by mass spectrometry. Moreover, four extracts inhibit cathepsin B, and Exaiptasia diaphana was selected for subsequent fractionation and characterization, resulting in the identification of betaine as being responsible for the inhibitory action. Both molecules are already found in marine organisms, however, this is the first study showing a potent inhibitory effect on caspase-1 and cathepsin B activities. Therefore, these new prototypes can be considered for the enzyme inhibition and subsequent control of the neuroinflammation.

Crotalphine Modulates Microglia M1/M2 Phenotypes and Induces Spinal Analgesia Mediated by Opioid-Cannabinoid Systems.

Pain is a worldwide public health problem and its treatment is still a challenge since clinically available drugs do not completely reverse chronic painful states or induce undesirable effects. Crotalphine is a 14 amino acids synthetic peptide that induces a potent and long-lasting analgesic effect on acute and chronic pain models, peripherally mediated by the endogenous release of dynorphin A and the desensitization of the transient receptor potential ankyrin 1 (TRPA1) receptor. However, the effects of crotalphine on the central nervous system (CNS) and the signaling pathway have not been investigated. Thus, the central effect of crotalphine was evaluated on the partial sciatic nerve ligation (PSNL)-induced chronic neuropathic pain model. Crotalphine (100 µg/kg, p.o.)-induced analgesia on the 14th day after surgery lasting up to 24 h after administration. This effect was prevented by intrathecal administration of CB1 (AM251) or CB2 (AM630) cannabinoid receptor antagonists. Besides that, crotalphine-induced analgesia was reversed by CTOP, nor-BNI, and naltrindole, antagonists of mu, kappa, and delta-opioid receptors, respectively, and also by the specific antibodies for ß-endorphin, dynorphin-A, and met-enkephalin. Likewise, the analgesic effect of crotalphine was blocked by the intrathecal administration of minocycline, an inhibitor of microglial activation and proliferation. Additionally, crotalphine decreased the PSNL-induced IL-6 release in the spinal cord. Importantly, in vitro, crotalphine inhibited LPS-induced CD86 expression and upregulated CD206 expression in BV-2 cells, demonstrating a polarization of microglial cells towards the M2 phenotype. These results demonstrated that crotalphine, besides activating opioid and cannabinoid analgesic systems, impairs central neuroinflammation, confirming the neuromodulatory mechanism involved in the crotalphine analgesic effect.

PKCζ-Mitogen-Activated Protein Kinase Signaling Mediates Crotalphine-Induced Antinociception.

Crotalphine (CRP) is a structural analogue to a peptide that was first identified in the crude venom from the South American rattlesnake Crotalus durissus terrificus. This peptide induces a potent and long-lasting antinociceptive effect that is mediated by the activation of peripheral opioid receptors. The opioid receptor activation regulates a variety of intracellular signaling, including the mitogen-activated protein kinase (MAPK) pathway. Using primary cultures of sensory neurons, it was demonstrated that crotalphine increases the level of activated ERK1/2 and JNK-MAPKs and this increase is dependent on the activation of protein kinase Cζ (PKCζ). However, whether PKCζ-MAPK signaling is critical for crotalphine-induced antinociception is unknown. Here, we biochemically demonstrated that the systemic crotalphine activates ERK1/2 and JNK and decreases the phosphorylation of p38 in the lumbar spinal cord. The in vivo pharmacological inhibition of spinal ERK1/2 and JNK, but not of p38, blocks the antinociceptive effect of crotalphine. Of interest, the administration of a PKCζ pseudosubstrate (PKCζ inhibitor) prevents crotalphine-induced ERK activation in the spinal cord, followed by the abolishment of crotalphine-induced analgesia. Together, our results demonstrate that the PKCζ-ERK signaling pathway is involved in crotalphine-induced analgesia. Our study opens a perspective for the PKCζ-MAPK axis as a target for pain control.

Activation of PKCε-ALDH2 Axis Prevents 4-HNE-Induced Pain in Mice.

Protein kinase Cε (PKCε) is highly expressed in nociceptor neurons and its activation has been reported as pro-nociceptive. Intriguingly, we previously demonstrated that activation of the mitochondrial PKCε substrate aldehyde dehydrogenase-2 (ALDH2) results in anti-nociceptive effects. ALDH2 is a major enzyme responsible for the clearance of 4-hydroxy-2-nonenal (4-HNE), an oxidative stress byproduct accumulated in inflammatory conditions and sufficient to induce pain hypersensitivity in rodents. Here we determined the contribution of the PKCε-ALDH2 axis during 4-HNE-induced mechanical hypersensitivity. Using knockout mice, we demonstrated that PKCε is essential for the nociception recovery during 4-HNE-induced hypersensitivity. We also found that ALDH2 deficient knockin mice display increased 4-HNE-induced nociceptive behavior. As proof of concept, the use of a selective peptide activator of PKCε (ΨεHSP90), which favors PKCε translocation to mitochondria and activation of PKCε-ALDH2 axis, was sufficient to block 4-HNE-induced hypersensitivity in WT, but not in ALDH2-deficient mice. Similarly, ΨεHSP90 administration prevented mechanical hypersensitivity induced by endogenous production of 4-HNE after carrageenan injection. These findings provide evidence that selective activation of mitochondrial PKCε-ALDH2 axis is important to mitigate aldehyde-mediated pain in rodents, suggesting that ΨεHSP90 and small molecules that mimic it may be a potential treatment for patients with pain.

Crotalphine Attenuates Pain and Neuroinflammation Induced by Experimental Autoimmune Encephalomyelitis in Mice.

Multiple sclerosis (MS) is a demyelinating disease of inflammatory and autoimmune origin, which induces sensory and progressive motor impairments, including pain. Cells of the immune system actively participate in the pathogenesis and progression of MS by inducing neuroinflammation, tissue damage, and demyelination. Crotalphine (CRO), a structural analogue to a peptide firstly identified in Crotalus durissus terrificus snake venom, induces analgesia by endogenous opioid release and type 2 cannabinoid receptor (CB2) activation. Since CB2 activation downregulates neuroinflammation and ameliorates symptoms in mice models of MS, it was presently investigated whether CRO has a beneficial effect in the experimental autoimmune encephalomyelitis (EAE). CRO was administered on the 5th day after immunization, in a single dose, or five doses starting at the peak of disease. CRO partially reverted EAE-induced mechanical hyperalgesia and decreased the severity of the clinical signs. In addition, CRO decreases the inflammatory infiltrate and glial cells activation followed by TNF-α and IL-17 downregulation in the spinal cord. Peripherally, CRO recovers the EAE-induced impairment in myelin thickness in the sciatic nerve. Therefore, CRO interferes with central and peripheral neuroinflammation, opening perspectives to MS control.

Neurotoxicity of Olindias sambaquiensis and Chiropsalmus quadrumanus extracts in sympathetic nervous system.

Cnidarians are equipped with nematocysts, which are specialized organelles used to inoculate venom during prey capturing and defense. Their venoms are rich in toxins and a potential source of bioactive compounds, however, poorly explored so far. In this work, the activity of the methanolic extracts from the hydromedusa Olindias sambaquiensis and the cubozoan jellyfish Chiropsalmus quadrumanus were studied in sympathetic neurotransmission. For that, bisected rat vas deferens - a classic model of sympathetic neurotransmission - were incubated with the extracts for further myographic and histopathological analysis. The O. sambaquiensis extract, at 0.1 µg/mL, facilitated the neurogenic contractions of the noradrenergic-rich epididymal portion, while reducing the noradrenaline (NA) potency, which suggests an interaction with postsynaptic α1-adrenoceptors. On the other hand, a higher concentration (1 µg/mL) leads to time- and frequency-dependent blockade of nerve-evoked contractions without significantly changing the response to exogenous NA. In turn, the C. quadrumanus extract at 0.1 µg/mL induced blockade of nerve-evoked noradrenergic contractions while reducing the potency to exogenous NA. Both extracts did not affect the purinergic neurotransmission or induce muscle damages. Our results demonstrate that O. sambaquiensis and C. quadrumanus extracts significantly interfere with the noradrenergic neurotransmission without altering purinergic response or smooth muscle structure on rat vas deferens. Such results bring to light the pharmacological potential of O. sambaquiensis and C. quadrumanus molecules for therapeutics focusing on noradrenergic neurotransmission.

Box Jellyfish (Cnidaria, Cubozoa) Extract Increases Neuron's Connection: A Possible Neuroprotector Effect.

Neurodegenerative diseases are one of the major causes of death worldwide, characterized by neurite atrophy, neuron apoptosis, and synapse loss. No effective treatment has been indicated for such diseases so far, and the search for new drugs is being increased in the last years. Animal venoms' secretion/venom can be an alternative for the discovery of new molecules, which could be the prototype for a new treatment. Here, we present the biochemical characterization and activity of the extract from the box jellyfish Chiropsalmus quadrumanus (Cq) on neurites. The Cq methanolic extract was obtained and incubated to human SH-SY5Y neurons, and neurite parameters were evaluated. The extract was tested in other cell types to check its cytotoxicity and was submitted to biochemical analysis by mass spectrometry in order to check its composition. We could verify that the Cq extract increased neurite outgrowth length and branching junctions, amplifying the contact between SH-SY5Y neurons, without affecting cell body and viability. The extract action was selective for neurons, as it did not cause any effects on other cell types, such as tumor line, nontumor line, and red blood cells. Moreover, mass spectrometry analysis revealed that there are no proteins but several low molecular mass compounds and peptides. Three peptides, characterized as cryptides, and 14 low molecular mass compounds were found to be related to cytoskeleton reorganization, cell membrane expansion, and antioxidant/neuroprotective activity, which act together to increase neuritogenesis. After this evaluation, we conclude that the Cq extract is a promising tool for neuronal connection recovery, an essential condition for the treatment of neurodegenerative diseases.

The Crotoxin:SBA-15 Complex Down-Regulates the Incidence and Intensity of Experimental Autoimmune Encephalomyelitis Through Peripheral and Central Actions.

Crotoxin (CTX), the main neurotoxin from Crotalus durissus terrificus snake venom, has anti-inflammatory, immunomodulatory and antinociceptive activities. However, the CTX-induced toxicity may compromise its use. Under this scenario, the use of nanoparticle such as nanostructured mesoporous silica (SBA-15) as a carrier might become a feasible approach to improve CTX safety. Here, we determined the benefits of SBA-15 on CTX-related neuroinflammatory and immunomodulatory properties during experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis that replicates several histopathological and immunological features observed in humans. We showed that a single administration of CTX:SBA-15 (54 µg/kg) was more effective in reducing pain and ameliorated the clinical score (motor impairment) in EAE animals compared to the CTX-treated EAE group; therefore, improving the disease outcome. Of interest, CTX:SBA-15, but not unconjugated CTX, prevented EAE-induced atrophy and loss of muscle function. Further supporting an immune mechanism, CTX:SBA-15 treatment reduced both recruitment and proliferation of peripheral Th17 cells as well as diminished IL-17 expression and glial cells activation in the spinal cord in EAE animals when compared with CTX-treated EAE group. Finally, CTX:SBA-15, but not unconjugated CTX, prevented the EAE-induced cell infiltration in the CNS. These results provide evidence that SBA-15 maximizes the immunomodulatory and anti-inflammatory effects of CTX in an EAE model; therefore, suggesting that SBA-15 has the potential to improve CTX effectiveness in the treatment of MS.

Mitochondrially-targeted treatment strategies.

Disruption of mitochondrial function is a common feature of inherited mitochondrial diseases (mitochondriopathies) and many other infectious and non-infectious diseases including viral, bacterial and protozoan infections, inflammatory and chronic pain, neurodegeneration, diabetes, obesity and cardiovascular diseases. Mitochondria therefore become an attractive target for developing new therapies. In this review we describe critical mechanisms involved in the maintenance of mitochondrial functionality and discuss strategies used to identify and validate mitochondrial targets in different diseases. We also highlight the most recent preclinical and clinical findings using molecules targeting mitochondrial bioenergetics, morphology, number, content and detoxification systems in common pathologies.

Mitogen-Activated Protein Kinase Signaling Mediates Morphine Induced-Delayed Hyperalgesia.

The use of morphine, the standard opioid drug, is limited by its undesirable effects, such as tolerance, physical dependence, and hyperalgesia (increased pain sensitivity). Clinical and preclinical studies have reported development of hyperalgesia after prolonged opioid administration or after a single dose of intrathecal (i.t.) morphine in uninjured rats. However, whether a single standard systemic morphine dose is sufficient to decrease the nociceptive threshold in rats is unknown. Here, we showed that a single morphine subcutaneous injection induces analgesia followed by a long-lasting delayed hyperalgesia in uninjured and PGE2 sensitized rats. The i.t injection of extracellular signal-regulated kinase (ERK) inhibitor blocked morphine-induced analgesia, without interfering with the morphine-induced hyperalgesia. However, i.t. injection of SB20358, a p38 inhibitor and SP660125, a JNK inhibitor, decreased the morphine-induced hyperalgesia. Consistently with the behavioral data, Western Blot analysis showed that ERK is more phosphorylated 1 h after morphine, i.e., when the analgesia is detected. Moreover, phospho-p38 and phospho-JNK levels are upregulated 96 h after morphine injection, time that coincides with the hyperalgesic effect. Intrathecal (i.t.) oligodeoxynucleotide (ODN) antisense to cAMP-responsive element binding protein (CREB) attenuated morphine-induced hyperalgesia. Real-time polymerase chain reaction (RT-PCR) analysis showed that CREB downstream genes expressions were significantly up-regulated 96 h after morphine injection in spinal cord. Together, our data suggest that central ERK is involved in the analgesic and hyperalgesic effects of morphine while JNK, p38, and CREB are involved in the morphine-induced delayed hyperalgesia.

Advanced glycation endproducts produced by in vitro glycation of type I collagen modulate the functional and secretory behavior of dorsal root ganglion cells cultivated in two-dimensional system.

Advanced glycation end-products (AGEs) are proteins/lipids that are glycated upon sugar exposure and are often increased during inflammatory diseases such as osteoarthritis and neurodegenerative disorders. Here, we developed an extracellular matrix (ECM) using glycated type I collagen (ECM-GC), which produced similar levels of AGEs to those detected in the sera of arthritic mice. In order to determine whether AGEs were sufficient to stimulate sensory neurons, dorsal root ganglia (DRGs) cells were cultured on ECM-GC or ECM-NC-coated plates. ECM-GC or ECM-NC were favorable for DRG cells expansion. However, ECM-GC cultivated neurons displayed thinner F-actin filaments, rounded morphology, and reduced neuron interconnection compared to ECM-NC. In addition, ECM-GC did not affect RAGE expression levels in the neurons, although induced rapid p38, MAPK and ERK activation. Finally, ECM-GC stimulated the secretion of nitrite and TNF-α by DRG cells. Taken together, our in vitro glycated ECM model suitably mimics the in vivo microenvironment of inflammatory disorders and provides new insights into the role of ECM impairment as a nociceptive stimulus.

Exercise Increases Insulin Sensitivity and Skeletal Muscle AMPK Expression in Systemic Lupus Erythematosus: A Randomized Controlled Trial.

Systemic lupus erythematosus (SLE) patients may show increased insulin resistance (IR) when compared with their healthy peers. Exercise training has been shown to improve insulin sensitivity in other insulin-resistant populations, but it has never been tested in SLE. Therefore, the aim of the present study was to assess the efficacy of a moderate-intensity exercise training program on insulin sensitivity and potential underlying mechanisms in SLE patients with mild/inactive disease. A 12-week, randomized controlled trial was conducted. Nineteen SLE patients were randomly assigned into two groups: trained (SLE-TR, n = 9) and non-trained (SLE-NT, n = 10). Before and after 12 weeks of the exercise training program, patients underwent a meal test (MT), from which surrogates of insulin sensitivity and beta-cell function were determined. Muscle biopsies were performed after the MT for the assessment of total and membrane GLUT4 and proteins related to insulin signaling [Akt and AMP-activated protein kinase (AMPK)]. SLE-TR showed, when compared with SLE-NT, significant decreases in fasting insulin [-39 vs. +14%, p = 0.009, effect size (ES) = -1.0] and in the insulin response to MT (-23 vs. +21%, p = 0.007, ES = -1.1), homeostasis model assessment IR (-30 vs. +15%, p = 0.005, ES = -1.1), a tendency toward decreased proinsulin response to MT (-19 vs. +6%, p = 0.07, ES = -0.9) and increased glucagon response to MT (+3 vs. -3%, p = 0.09, ES = 0.6), and significant increases in the Matsuda index (+66 vs. -31%, p = 0.004, ES = 0.9) and fasting glucagon (+4 vs. -8%, p = 0.03, ES = 0.7). No significant differences between SLT-TR and SLT-NT were observed in fasting glucose, glucose response to MT, and insulinogenic index (all p > 0.05). SLE-TR showed a significant increase in AMPK Thr 172 phosphorylation when compared to SLE-NT (+73 vs. -12%, p = 0.014, ES = 1.3), whereas no significant differences between groups were observed in Akt Ser 473 phosphorylation, total and membrane GLUT4 expression, and GLUT4 translocation (all p > 0.05). In conclusion, a 12-week moderate-intensity aerobic exercise training program improved insulin sensitivity in SLE patients with mild/inactive disease. This effect appears to be partially mediated by the increased insulin-stimulated skeletal muscle AMPK phosphorylation. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT01515163.

Increased Insulin Resistance and Glucagon Levels in Mild/Inactive Systemic Lupus Erythematosus Patients Despite Normal Glucose Tolerance.

OBJECTIVE: To assess insulin sensitivity in patients with systemic lupus erythematosus (SLE) in response to a meal tolerance test (MTT). METHODS: In this cross-sectional study, 33 adult females with mild/inactive SLE (SLE group) and 16 age- and body mass index-matched female healthy controls (CTRL group) underwent an MTT and were assessed for insulin sensitivity and beta cell function. Skeletal muscle protein expressions of total and membrane insulin-dependent glucose transporter 4 (GLUT-4) were also evaluated (SLE group: n = 10, CTRL group: n = 5); muscle biopsies were performed after MTT. Further measurements included inflammatory cytokines, adipocytokines, physical activity level, body composition, and food intake. RESULTS: SLE and CTRL groups showed similar fasting glucose, glucose response, and skeletal muscle GLUT-4 translocation after MTT. However, the SLE group demonstrated higher fasting insulin levels (P = 0.01; effect size [ES] 1.2), homeostatic model assessment insulin resistance (IR) (P = 0.03; ES 1.1), insulin-to-glucose ratio response to MTT (P = 0.02; ES 1.2), fasting glucagon levels (P = 0.002; ES 2.7), glucagon response to MTT (P = 0.0001; ES 2.6), and a tendency toward lower Matsuda index of whole-body insulin sensitivity (P = 0.06; ES -0.5) when compared with the CTRL group. Fasting proinsulin-to-insulin ratio and proinsulin-to-insulin ratio response to MTT were similar between groups (P > 0.05), while the SLE group showed a higher insulinogenic index when compared with the CTRL group (P = 0.02; ES = 0.9). CONCLUSION: We have identified that SLE patients had a bi-hormone metabolic abnormality characterized by increased IR and hyperglucagonemia despite normal glucose tolerance and preserved beta cell function and skeletal muscle GLUT-4 translocation. Strategies capable of ameliorating insulin sensitivity to reduce the risk of type 2 diabetes mellitus and cardiovascular disease in SLE may require more than targeting IR alone.

Crotoxin, a rattlesnake toxin, down-modulates functions of bone marrow neutrophils and impairs the Syk-GTPase pathway.

Neutrophils have a critical role in the innate immune response; these cells represent the primary line of defense against invading pathogens or tissue injury. Crotoxin (CTX), the major toxin of the South American rattlesnake (Crotalus durissus terrificus) venom, presents longstanding anti-inflammatory properties, inhibiting neutrophil migration and phagocytosis by peritoneal neutrophils for 14 days. Herein, to elucidate these sustained inhibitory effects induced by CTX, we performed in vitro and in vivo studies evaluating the functionality of bone marrow neutrophils and possible molecular mechanisms associated with these effects. CTX inhibited the processes of chemotaxis, adhesion to fibronectin, and phagocytosis of opsonized particles; however, it did not affect ROS production or degranulation in bone marrow neutrophils. To understand the molecular mechanisms that orchestrate this effect, we investigated the expression of CR3 on the neutrophil surface and the total expression and activity of signaling proteins from the Syk-GTPase pathway, which is involved in actin polymerization. CTX down-regulated both subunits of CR3, as well as, the activity of Syk, Vav1, Cdc42, Rac1 and RhoA, and the expression of the subunit 1B from Arp2/3. Together, our findings demonstrated that CTX inhibits the functionally of bone marrow neutrophils and that this effect may be associated with an impairment of the Syk-GTPase pathway. This study demonstrates, for the first time, that the sustained down-modulatory effect of CTX on circulating and peritoneal neutrophils is associated with functional modifications of neutrophils still in the bone marrow, and it also contributes to a better understanding of the anti-inflammatory effect of CTX.