Ibudilast attenuates doxorubicin-induced cytotoxicity by suppressing formation of TRPC3 channel and NADPH oxidase 2 protein complexes.

BACKGROUND AND PURPOSE: Doxorubicin is a highly effective anticancer agent but eventually induces cardiotoxicity associated with increased production of ROS. We previously reported that a pathological protein interaction between TRPC3 channels and NADPH oxidase 2 (Nox2) contributed to doxorubicin-induced cardiac atrophy in mice. Here we have investigated the effects of ibudilast, a drug already approved for clinical use and known to block doxorubicin-induced cytotoxicity, on the TRPC3-Nox2 complex. We specifically sought evidence that this drug attenuated doxorubicin-induced systemic tissue wasting in mice. EXPERIMENTAL APPROACH: We used the RAW264.7 macrophage cell line to screen 1,271 clinically approved chemical compounds, evaluating functional interactions between TRPC3 channels and Nox2, by measuring Nox2 protein stability and ROS production, with and without exposure to doxorubicin. In male C57BL/6 mice, samples of cardiac and gastrocnemius muscle were taken and analysed with morphometric, immunohistochemical, RT-PCR and western blot methods. In the passive smoking model, cells were exposed to DMEM containing cigarette sidestream smoke. KEY RESULTS: Ibudilast, an anti-asthmatic drug, attenuated ROS-mediated muscle toxicity induced by doxorubicin treatment or passive smoking, by inhibiting the functional interactions between TRPC3 channels and Nox2, without reducing TRPC3 channel activity. CONCLUSIONS AND IMPLICATIONS: These results indicate a common mechanism underlying induction of systemic tissue wasting by doxorubicin. They also suggest that ibudilast could be repurposed to prevent muscle toxicity caused by anticancer drugs or passive smoking.

Biochanin A prevents 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced adipocyte dysfunction in cultured 3T3-L1 cells.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental pollutant. TCDD accumulates in the food chain, mainly in the fatty tissues of the human body where it causes various toxic effects. Biochanin A is a natural organic compound in the class of phytochemicals known as flavonoids. We investigated whether biochanin A suppresses TCDD-induced loss of adipogenic action using 3T3-L1 adipocytes as a cell culture model of wasting syndrome. In the present study, biochanin A suppressed TCDD-induced loss of lipid accumulation. Pretreating the cells with biochanin A increased the levels of the adipogenesis-associated factors peroxisome proliferator-activated receptor γ and adiponectin, which were inhibited by TCDD. TCDD decreased insulin-stimulated glucose uptake, which was effectively restored by pretreatment with biochanin A. Biochanin A also inhibited the TCDD-driven decrease in production of insulin receptor substrate-1 and glucose transporter 4. These results suggest a preventive effect of biochanin A against TCDD in the development of insulin resistance and diabetes. TCDD increased production of intracellular calcium ([Ca2+]i), prostaglandin E2, cytosolic phospholipase A2, and cyclooxygenase-1, while reducing the level of peroxisome proliferator-activated receptor gamma coactivator 1-alpha. However, biochanin A inhibited these TCDD-induced effects. We conclude that biochanin A is an attractive compound for preventing TCDD-induced wasting syndrome.

Hepatocyte-Specific Deletion of TIPARP, a Negative Regulator of the Aryl Hydrocarbon Receptor, Is Sufficient to Increase Sensitivity to Dioxin-Induced Wasting Syndrome.

The aryl hydrocarbon receptor (AHR) mediates the toxic effects of dioxin (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin; TCDD), which includes thymic atrophy, steatohepatitis, and a lethal wasting syndrome in laboratory rodents. Although the mechanisms of dioxin toxicity remain unknown, AHR signaling in hepatocytes is necessary for dioxin-induced liver toxicity. We previously reported that loss of TCDD-inducible poly(adenosine diphosphate [ADP]-ribose) polymerase (TIPARP/PARP7/ARTD14), an AHR target gene and mono-ADP-ribosyltransferase, increases the sensitivity of mice to dioxin-induced toxicities. To test the hypothesis that TIPARP is a negative regulator of AHR signaling in hepatocytes, we generated Tiparpfl/fl mice in which exon 3 of Tiparp is flanked by loxP sites, followed by Cre-lox technology to create hepatocyte-specific (Tiparpfl/flCreAlb) and whole-body (Tiparpfl/flCreCMV; TiparpEx3-/-) Tiparp null mice. Tiparpfl/flCreAlb and TiparpEx3-/- mice given a single injection of 10 µg/kg dioxin did not survive beyond days 7 and 9, respectively, while all Tiparp+/+ mice survived the 30-day treatment. Dioxin-exposed Tiparpfl/flCreAlb and TiparpEx3-/- mice had increased steatohepatitis and hepatotoxicity as indicated by greater staining of neutral lipids and serum alanine aminotransferase activity than similarly treated wild-type mice. Tiparpfl/flCreAlb and TiparpEx3-/- mice exhibited augmented AHR signaling, denoted by increased dioxin-induced gene expression. Metabolomic studies revealed alterations in lipid and amino acid metabolism in liver extracts from Tiparpfl/flCreAlb mice compared with wild-type mice. Taken together, these data illustrate that TIPARP is an important negative regulator of AHR activity, and that its specific loss in hepatocytes is sufficient to increase sensitivity to dioxin-induced steatohepatitis and lethality.

Changes in body composition and muscle attenuation during taxane-based chemotherapy in patients with metastatic breast cancer.

PURPOSE: Body composition parameters including low muscle mass, muscle attenuation (which reflects muscle quality) and adipose tissue measurements have emerged as prognostic factors in cancer patients. However, knowledge regarding the possibility of excessive muscle loss during specific systemic therapies is unknown. We describe the changes in body composition and muscle attenuation (MA) during taxane- and anthracycline-based regimens and its association with overall survival (OS) in metastatic breast cancer patients. METHODS: The lumbar skeletal muscle index (LSMI) was used as marker of muscle mass. LSMI, MA, subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT) and intramuscular adipose tissue (IMAT) were measured before and after first-line treatment with paclitaxel (n = 73) or 5-fluorouracil-doxorubicin-cyclophosphamide (FAC) (n = 25) using CT-images. Determinants of the change of LSMI and MA were analyzed using multiple linear regression. OS was assessed using Cox proportional hazard models. RESULTS: MA significantly decreased during paclitaxel treatment (- 0.9 HU, p = 0.03). LSMI (p = 0.40), SAT (p = 0.75), VAT (p = 0.84) and IMAT (p = 0.10) remained stable. No significant alterations in body composition parameters during FAC-treatment were observed. Previous (neo-)adjuvant chemotherapy contributed to larger loss of MA during the current treatment. Body composition changes during chemotherapy were not associated with OS. CONCLUSIONS: MA decreased during treatment with paclitaxel, while muscle mass was stable. Body composition changes are not associated with survival in the absence of progressive disease.

Mitochondria: Inadvertent targets in chemotherapy-induced skeletal muscle toxicity and wasting?

Chemotherapy has been associated with increased mitochondrial reactive oxygen species production, mitochondrial dysfunction and skeletal muscle atrophy leading to severe patient clinical complications including skeletal muscle fatigue, insulin resistance and wasting. The exact mechanisms behind this skeletal muscle toxicity are largely unknown, and as such co-therapies to attenuate chemotherapy-induced side effects are lacking. Here, we review the current literature describing the clinical manifestations and molecular origins of chemotherapy-induced myopathy with a focus on the mitochondria as the target organelle via which chemotherapeutic agents establish toxicity. We explore the likely mechanisms through which myopathy is induced, using the anthracycline doxorubicin, and the platinum-based alkylating agent oxaliplatin, as examples. Finally, we recommend directions for future research and outline the potential significance of these proposed directions.

Central Diabetes Insipidus and Cisplatin-Induced Renal Salt Wasting Syndrome: A Challenging Combination.

We describe a 2-year-old female with a suprasellar primitive neuroectodermal tumor and central diabetes insipidus (DI) who developed polyuria with natriuresis and subsequent hyponatremia 36 hr after cisplatin administration. The marked urinary losses of sodium in combination with a negative sodium balance led to the diagnosis of cisplatin-induced renal salt wasting syndrome (RSWS). The subsequent clinical management is very challenging. Four weeks later she was discharged from ICU without neurological sequela. The combination of cisplatin-induced RSWS with DI can be confusing and needs careful clinical assessment as inaccurate diagnosis and management can result in increased neurological injury.

[Effect of Cynaropicrin on 2,3,4,7,8-Pentachlorodibenzofuran-induced Wasting Syndrome and Oxidative Stress].

The effect of cynaropicrin that is the major component of an edible plant, artichoke (Cynara scolymus) on 2,3,4,7,8-pentachlorodibenzofuran (PenCDF)-induced toxicity in mice was studied. We evaluated the effect of cynaropicrin on the wasting syndrome and oxidative stress elicited by PenCDF. However, the PenCDF dose-response relationship on the wasting syndrome has been superficial. Therefore, we determined the dose which causes wasting syndrome in C57BL/6J mice, a responsive strain to dioxins. Since 2,3,7,8-tetrachlorodibenzo-p-dioxin (0.1 mg/kg, p.o.) induces hepatic ethoxyresorfin O-deethylase (EROD) activity in mice, we set the doses of PenCDF at 0.3, 1.0, 3.0, 5.0 and 10 mg/kg (once, p.o.) on the basis of its toxic-eqivalency factor (0.3). The wasting syndrome was evaluated by measuring the daily changes of body weight. Thiobarbituric acid-reactive substances were used as an index of oxidative stress. Of PenCDF doses examined, wasting syndrome and oxidative stress took place most markedly in 5 mg/kg. In disagreement with this, EROD activity which is the marker of the aryl hydrocarbon receptor-dependent induction of cytochrome P450 1a1 was elevated most abundantly at 0.3 mg/kg. Then, we examined the effect of cynaropicrin on the wasting syndrome and oxidative stress provoked by PenCDF at 5 mg/kg. However, this compound up to 20 mg/kg (p.o.) did not attenuate PenCDF-induced wasting syndrome. On the contray, PenCDF-induced oxidateive stress was suppressed by cynaropicrin at the highest dose (20 mg/kg), although EROD activity was increased rather than reduced by cynaropicrin at lower doses. Thus, it is suggested that cynaropicrin has an ability to reduce oxidative stress caused by PenCDF.

Transcriptional profiling of rat hypothalamus response to 2,3,7,8-tetrachlorodibenzo-ρ-dioxin.

In some mammals, halogenated aromatic hydrocarbon (HAH) exposure causes wasting syndrome, defined as significant weight loss associated with lethal outcomes. The most potent HAH in causing wasting is 2,3,7,8-tetrachlorodibenzo-ρ-dioxin (TCDD), which exerts its toxic effects through the aryl hydrocarbon receptor (AHR). Since TCDD toxicity is thought to predominantly arise from dysregulation of AHR-transcribed genes, it was hypothesized that wasting syndrome is a result of to TCDD-induced dysregulation of genes involved in regulation of food-intake. As the hypothalamus is the central nervous systems' regulatory center for food-intake and energy balance. Therefore, mRNA abundances in hypothalamic tissue from two rat strains with widely differing sensitivities to TCDD-induced wasting syndrome: TCDD-sensitive Long-Evans rats and TCDD-resistant Han/Wistar rats, 23h after exposure to TCDD (100µg/kg) or corn oil vehicle. TCDD exposure caused minimal transcriptional dysregulation in the hypothalamus, with only 6 genes significantly altered in Long-Evans rats and 15 genes in Han/Wistar rats. Two of the most dysregulated genes were Cyp1a1 and Nqo1, which are induced by TCDD across a wide range of tissues and are considered sensitive markers of TCDD exposure. The minimal response of the hypothalamic transcriptome to a lethal dose of TCDD at an early time-point suggests that the hypothalamus is not the predominant site of initial events leading to hypophagia and associated wasting. TCDD may affect feeding behaviour via events upstream or downstream of the hypothalamus, and further work is required to evaluate this at the level of individual hypothalamic nuclei and subregions.

The posterior cricoarytenoid muscle is spared from MuRF1-mediated muscle atrophy in mice with acute lung injury.

BACKGROUND: Skeletal muscle wasting in acute lung injury (ALI) patients increases the morbidity and mortality associated with this critical illness. The contribution of laryngeal muscle wasting to these outcomes is unknown, though voice impairments and aspiration are common in intensive care unit (ICU) survivors. We evaluated the intrinsic laryngeal abductor (PCA, posterior cricoarytenoid), adductor (CT, cricothyroid) and limb (EDL, extensor digitorum longus) muscles in a mouse model of ALI. METHODS: Escherichia coli lipopolysaccharides were instilled into the lungs of adult male C57Bl6J mice (ALI mice). Limb and intrinsic laryngeal muscles were analyzed for fiber size, type, protein expression and myosin heavy chain (MyHC) composition by SDS-PAGE and mass spectroscopy. RESULTS: Marked muscle atrophy occurred in the CT and EDL muscles, while the PCA was spared. The E3 ubiquitin ligase muscle ring finger-1 protein (MuRF1), a known mediator of limb muscle atrophy in this model, was upregulated in the CT and EDL, but not in the PCA. Genetic inhibition of MuRF1 protected the CT and EDL from ALI-induced muscle atrophy. MyHC-Extraocular (MyHC-EO) comprised 27% of the total MyHC in the PCA, distributed as hybrid fibers throughout 72% of PCA muscle fibers. CONCLUSION: The vocal cord abductor (PCA) contains a large proportion of fibers expressing MyHC-EO and is spared from muscle atrophy in ALI mice. The lack of MuRF1 expression in the PCA suggests a previously unrecognized mechanism whereby this muscle is spared from atrophy. Atrophy of the vocal cord adductor (CT) may contribute to the impaired voice and increased aspiration observed in ICU survivors. Further evaluation of the sparing of muscles involved in systemic wasting diseases may lead to potential therapeutic targets for these illnesses.

Cushing syndrome and giant sterile abscess induced by self intramuscular injection of supra-therapeutic doses of triamcinolone.

OBJECTIVE: Corticosteroid are among the most commonly used medications for a wide range of inflammatory, autoimmune and neoplastic disorders. Therefore, it is important for the physician to be aware of their side effects, in relation to different forms and delivery, that occur more often with oral therapy. METHODS: A 33-year old professional drummer had been suffering from bilateral tenosynovitis of the wrists for three months. In order to accelerate the recovery and play drums again, he self-injected supra-therapeutic doses of triamcinolone acetonide (a total of injected drug > 2,400 mg was calculated) in his right gluteus. RESULTS: The intramuscular overuse of triamcinolone acetonide caused Cushing syndrome associated with a giant sterile abscess that involved the right gluteal muscles and the adjacent subcutaneous tissue. CONCLUSION: A large intramuscular sterile abscess can be a side effect of supra-therapeutic intramuscular triamcinolone dose and this should be explained to the patient prior to initiation of treatment with triamcinolone.

Selenium-binding protein 1: its physiological function, dependence on aryl hydrocarbon receptors, and role in wasting syndrome by 2,3,7,8-tetrachlorodibenzo-p-dioxin.

BACKGROUND: Selenium-binding protein 1 (Selenbp1) is suggested to play a role in tumor suppression, and may be involved in the toxicity produced by dioxin, an activator of aryl hydrocarbon receptors (AhR). However, the mechanism or likelihood is largely unknown because of the limited information available about the physiological role of Selenbp1. METHODS: To address this issue, we generated Selenbp1-null [Selenbp1 (-/-)] mice, and examined the toxic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in this mouse model. RESULTS: Selenbp1 (-/-) mice exhibited only a few differences from wild-type mice in their apparent phenotypes. However, a DNA microarray experiment showed that many genes including Notch1 and Cdk1, which are known to be enhanced in ovarian carcinoma, are also increased in the ovaries of Selenbp1 (-/-) mice. Based on the different responses to TCDD between C57BL/6J and DBA/2J strains of mice, the expression of Selenbp1 is suggested to be under the control of AhR. However, wasting syndrome by TCDD occurred equally in Selenbp1 (-/-) and (+/+) mice. CONCLUSIONS: The above pieces of evidence suggest that 1) Selenbp1 suppresses the expression of tumor-promoting genes although a reduction in Selenbp1 alone is not very serious as far as the animals are concerned; and 2) Selenbp1 induction by TCDD is neither a pre-requisite for toxicity nor a protective response for combating TCDD toxicity. GENERAL SIGNIFICANCE: Selenbp1 (-/-) mice exhibit little difference in their apparent phenotype and responsiveness to dioxin compared with the wild-type. This may be due to the compensation of Selenbp1 function by a closely-related protein, Selenbp2.

Angiotensin II induced catabolic effect and muscle atrophy are redox dependent.

Angiotensin II (Ang II) causes skeletal muscle wasting via an increase in muscle catabolism. To determine whether the wasting effects of Ang II were related to its ability to increase NADPH oxidase-derived reactive oxygen species (ROS) we infused wild-type C57BL/6J or p47(phox)(-/-) mice with vehicle or Ang II for 7days. Superoxide production was increased 2.4-fold in the skeletal muscle of Ang II infused mice, and this increase was prevented in p47(phox)(-/-) mice. Apocynin treatment prevented Ang II-induced superoxide production in skeletal muscle, consistent with Ang II increasing NADPH oxidase derived ROS. Ang II induced loss of body and skeletal muscle weight in C57BL/6J mice, whereas the reduction was significantly attenuated in p47(phox)(-/-) animals. The reduction of skeletal muscle weight caused by Ang II was associated with an increase of proteasome activity, and this increase was completely prevented in the skeletal muscle of p47(phox)(-/-) mice. In conclusion, Ang II-induced skeletal muscle wasting is in part dependent on NADPH oxidase derived ROS.

Dietary zinc mediates inflammation and protects against wasting and metabolic derangement caused by sustained cigarette smoke exposure in mice.

In mouse asthma models, inflammation can be modulated by zinc (Zn). Given that appetite loss, muscle wasting and poor nutrition are features of chronic obstructive pulmonary disease (COPD) and that poor dietary Zn intake is in itself accompanied by growth retardation and appetite loss, we hypothesised that dietary Zn limitation would not only worsen airway inflammation but also exaggerate metabolic effects of cigarette smoke (CS) exposure in mice. Conversely, Zn supplementation would lessen inflammation. Mice were exposed to CS [2× 2RF, 3×/day; 15 min/cigarette] and fed diets containing 2, 20 or 140 mg/kg Zn ad libitum. Airway cells were collected by bronchoalveolar lavage (BAL). Plasma Zn was measured by fluorometric assay. Inflammatory, metabolic and Zn transport markers were measured by real-time RT-PCR. Mice fed low Zn diets had less plasma labile zinc (0-0.18 µM) than mice fed moderate (0.61-0.98 µM) or high (0.77-1.1 µM) Zn diets (SDs 0.1-0.4, n = 8-10). Smoke exposure increased plasma and BAL labile Zn (1.5-2.5 fold, P < 0.001), bronchoalveolar macrophages (2.0 fold, P < 0.0001) and MT-1 (1.5 fold), MIP-2 (2.3 fold) and MMP-12 (3.5 fold) mRNA. Zn supplementation reduced alveolar macrophage numbers by 62 and 52% in sham and smoke-exposed mice, respectively (Zn effect: P = 0.011). Gastrocnemius, soleus and tibialis anterior muscle mass were affected by both smoke and dietary Zn in the order of 3-7%. The 50-60% reduction in alveolar macrophages in Zn-supplemented mice supports our evolving hypothesis that Zn is an important anti-inflammatory mediator of airway inflammation. Restoring airway Zn levels through dietary supplementation may lessen the severity of lung inflammation when Zn intake is low.

Dioxins, the aryl hydrocarbon receptor and the central regulation of energy balance.

Dioxins are ubiquitous environmental contaminants that have attracted toxicological interest not only for the potential risk they pose to human health but also because of their unique mechanism of action. This mechanism involves a specific, phylogenetically old intracellular receptor (the aryl hydrocarbon receptor, AHR) which has recently proven to have an integral regulatory role in a number of physiological processes, but whose endogenous ligand is still elusive. A major acute impact of dioxins in laboratory animals is the wasting syndrome, which represents a puzzling and dramatic perturbation of the regulatory systems for energy balance. A single dose of the most potent dioxin, TCDD, can permanently readjust the defended body weight set-point level thus providing a potentially useful tool and model for physiological research. Recent evidence of response-selective modulation of AHR action by alternative ligands suggests further that even therapeutic implications might be possible in the future.

Association of skeletal muscle wasting with treatment with sorafenib in patients with advanced renal cell carcinoma: results from a placebo-controlled study.

PURPOSE Effects of specific antineoplastic therapies on progression of cancer-associated wasting remain uncharacterized. We selected a targeted therapy, sorafenib, because of its reported association with weight loss. PATIENTS AND METHODS Patients with metastatic renal cell cancer (RCC) who were resistant to standard therapy (N = 80) received sorafenib 400 mg twice daily or placebo in a randomized, double-blinded clinical trial. Computed tomography image analysis, which has high precision and specificity for evaluation of specific muscles and adipose tissues, was used to define change in total skeletal muscle and adipose tissue. Results At inclusion, 51% of patients were overweight or obese (ie, body mass index [BMI] > 25 kg/m(2)). Only 5% were underweight. Advanced muscle wasting (ie, sarcopenia) was present in 72% of patients with BMI less than 25 and in 34% of those with a BMI greater than 25. Patients received placebo for an average of 6 months and received sorafenib for 1 year. Patients in the placebo group had stable body weight during 6 months (0.8 kg +/- 0.7 kg), with no significant alteration of muscle or fat. Patients who received sorafenib lost 2.1 kg +/- 0.6 kg (P < .01) in 6 months and lost 4.2 kg +/- 0.7 kg (P < .01) by 1 year. Sorafenib-treated patients lost skeletal muscle progressively at 6 months (decrease of 4.9%; P < .01) and 12 months (decrease of 8.0%; P < .01). CONCLUSION Sarcopenia is prevalent in patients with metastatic RCC and is an occult condition in patients with normal or high BMI. Muscle loss is specifically exacerbated by sorafenib, consistent with the evidence for a role of kinases in regulating muscle mass. Muscle loss is a sorafenib adverse effect that may relate to asthenia, fatigue, and physical disability.

Involvement of SREBPs in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced disruption of lipid metabolism in male guinea pig.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has multiple toxic effects causing a wasting syndrome characterized by a loss of body weight accompanied by a decrease in adipose tissue weight. To elucidate the mechanism behind this syndrome, we investigated the changes in lipid metabolism 7 and 21 days after a single intraperitoneal injection of TCDD at 1 microg/kg body weight to male guinea pigs. TCDD caused the symptoms of the syndrome, body weight loss with a decrease in adipose tissue weight, while it increased the levels of triacylglycerols, total cholesterols, and free fatty acids in plasma. On day 7, TCDD decreased the levels of CCAAT/enhancer binding protein (C/EBP) alpha, peroxisome proliferator activated receptor gamma, and glucose transporter 4, adipogenesis-related factors, in adipose tissue, whereas the levels of retinoid X receptor alpha, C/EBPbeta, C/EBPdelta, and c-Myc remained unchanged. TCDD also reduced the levels of both p125 precursor and p68 active forms of sterol regulatory element binding protein (SREBP)-1 and -2, the lipogenesis-related factors, and downregulated their DNA binding activity in adipose tissue, while it raised the levels of their p68 active forms and increased their DNA binding activity in the liver. TCDD decreased mRNA and protein levels of acetyl-CoA carboxylase and HMG-CoA synthase in the liver and adipose tissue. Similar results were obtained on day 21. These results suggest that TCDD disrupts lipid metabolism through changes in the expression levels of the adipogenesis-related and lipogenesis-related proteins in the liver and adipose tissue, and SREBPs would be involved in the development of the wasting syndrome.

High doses of stavudine induce fat wasting and mild liver damage without impairing mitochondrial respiration in mice.

OBJECTIVE: Stavudine (d4T), a nucleoside reverse-transcriptase inhibitor (NRTI), can induce lipoatrophy, fatty liver, hyperlactataemia and abnormal liver tests. NRTI toxicity is usually ascribed to mitochondrial DNA (mtDNA) depletion and impaired mitochondrial respiration. However, NRTIs could have effects unrelated to mtDNA. Recently, we reported that 100 mg/kg/day of d4T stimulated fatty acid oxidation (FAO) in mouse liver, and reduced body fatness without depleting white adipose tissue (WAT) mtDNA. We hypothesized that higher d4T doses could further reduce adiposity, while inhibiting hepatic FAO. METHODS: Mice were treated for 2 weeks with d4T (500 mg/kg/day), L-carnitine (200 mg/kg/day) or both drugs concomitantly. Body fatness was assessed by dual energy X-ray absorptiometry, and investigations were performed in plasma, liver, muscle and WAT. RESULTS: D4T reduced the gain of body adiposity, WAT leptin, whole body FAO and plasma ketone bodies, and increased liver triglycerides and plasma aminotransferases with mild ultrastructural abnormalities in hepatocytes. Plasma lactate and respiratory chain activities in tissues were unchanged. Stearoyl-CoA desaturase (SCD-1), an enzyme negatively regulated by leptin, was overexpressed in liver. High doses of beta-aminoisobutyric acid (BAIBA), a d4T catabolite, increased plasma ketone bodies. Although L-carnitine did not correct body adiposity, it prevented d4T-induced impairment of FAO and liver abnormalities. CONCLUSIONS: D4T overdosage triggers fat wasting, leptin insufficiency and mild liver damage, without causing respiratory chain dysfunction. Overexpression of SCD-1 reduces fatty acid oxidation and overcomes the stimulating effect of BAIBA on hepatic FAO. L-carnitine does not correct leptin insufficiency but prevents d4T-induced impairment of FAO and liver damage.

UCP3 in muscle wasting, a role in modulating lipotoxicity?

UCP3 has been postulated to function in the defense against lipid-induced oxidative muscle damage (lipotoxicity). We explored this hypothesis during cachexia in rats (zymosan-induced sepsis), a condition characterized by increased oxidative stress and supply of fatty acids to the muscle. Muscle UCP3 protein content was increased 2, 6 and 11 days after zymosan injection. Plasma FFA levels were increased at day 2, but dropped below control levels on days 6 and 11. Muscular levels of the lipid peroxidation byproduct 4-hydroxy-2-nonenal (4-HNE) were increased at days 6 and 11 in zymosan-treated rats, supporting a role for UCP3 in modulating lipotoxicity during cachexia.

Antisense therapy of MAdCAM-1 for trinitrobenzenesulfonic acid-induced murine colitis.

BACKGROUND: Anti-alpha4 integrin reagent, natalizumab, which is 1 of the most promising antiadhesion monoclonal antibodies, has been introduced into clinical trials against inflammatory bowel disease (IBD). Lethal consequences such as progressive multifocal leukoencephalopathy have recently been reported in patients using natalizumab, making it critical to determine which selective adhesion molecule in the alpha4 integrins-dependent pathway should be targeted for inhibition and the minimal spectrum of activity required for the valid treatment of IBD. Mucosal addressin cell adhesion molecule (MAdCAM)-1 is known to be restrictedly expressed in gut-associated lymphoid tissues, and its expression dramatically increases in IBD. This study aimed to reevaluate the effectiveness of MAdCAM-1 inhibition and to determine the feasibility of anti-MAdCAM-1 strategy. MATERIALS AND METHODS: Antisense MAdCAM-1 oligonucleotides were injected into mice at 1.5 mg/kg/day for 7 consecutive days from the first day of a trinitrobenzene sulfonate enema. RESULTS: MAdCAM-1 antisense oligonucleotides significantly suppressed the development of trinitrobenzene sulfonate colitis clinically and histopathologically compared with controls. Immunohistochemistry and semiquantitative reverse-transcription polymerase chain reaction of the colon tissues revealed that MAdCAM-1 protein and mRNA expression were lower in antisense-treated mice than in controls. In addition, MAdCAM-1 antisense treatment reduced the number of alpha4beta7 lymphocytes in the inflamed colonic mucosa. CONCLUSIONS: These data suggest that antisense suppression of MAdCAM-1 is of equivalent effectiveness to that of anti-MAdCAM-1 or anti-alpha4 integrin antibody in previous reports and could be a new therapy for IBD.

Muscle-specific expression of IGF-1 blocks angiotensin II-induced skeletal muscle wasting.

Advanced congestive heart failure is associated with activation of the renin-angiotensin system and skeletal muscle wasting. We previously showed that angiotensin II infusion in rats produces cachexia secondarily to increased muscle proteolysis and also decreases levels of circulating and skeletal muscle IGF-1. Here we show that angiotensin II markedly downregulates phospho-Akt and activates caspase-3 in skeletal muscle, leading to actin cleavage, an important component of muscle proteolysis, and to increased apoptosis. These changes are blocked by muscle-specific expression of IGF-1, likely via the Akt/mTOR/p70S6K signaling pathway. We also demonstrate that mRNA levels of the ubiquitin ligases atrogin-1 and muscle ring finger-1 are upregulated in angiotensin II-infused WT, but not in IGF-1-transgenic, mice. These findings strongly suggest that angiotensin II downregulation of IGF-1 in skeletal muscle is causally related to angiotensin II-induced wasting. Because the renin-angiotensin system is activated in many catabolic conditions, our findings have broad implications for understanding mechanisms of skeletal muscle wasting and provide a rationale for new therapeutic approaches.