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Cachexia, the metabolic dysregulation leading to sustained loss of muscle and adipose tissue, is a devastating complication of cancer and other chronic diseases. Interleukin-6 and related cytokines are associated with muscle wasting in clinical and experimental cachexia, although the mechanisms by which they might induce muscle wasting are unknown. One pathway activated strongly by IL-6 family ligands is the JAK/STAT3 pathway, the function of which has not been evaluated in regulation of skeletal muscle mass. Recently, we showed that skeletal muscle STAT3 phosphorylation, nuclear localization, and target gene expression are activated in C26 cancer cachexia, a model with high IL-6 family ligands. Here, we report that STAT3 activation is a common feature of muscle wasting, activated in muscle by IL-6 in vivo and in vitro and by different types of cancer and sterile sepsis. Moreover, STAT3 activation proved both necessary and sufficient for muscle wasting. In C2C12myotubes and in mouse muscle, mutant constitutively activated STAT3-induced muscle fiber atrophy and exacerbated wasting in cachexia. Conversely, inhibiting STAT3 pharmacologically with JAK or STAT3 inhibitors or genetically with dominant negative STAT3 and short hairpin STAT3 reduced muscle atrophy downstream of IL-6 or cancer. These results indicate that STAT3 is a primary mediator of muscle wasting in cancer cachexia and other conditions of high IL-6 family signaling. Thus STAT3 could represent a novel therapeutic target for the preservation of skeletal muscle in cachexia.

Salt-sensitive (SS) hypertension is a vascular diathesis characterized by reduced cardiovascular and renal nitric oxide bioavailability and local upregulation of ANG II. We have demonstrated that rats infused with ANG II manifest increased cortical cyclooxygenase (COX)-2 expression and activity via NADPH oxidase-derived reactive oxygen species (ROS). In the present studies we used Dahl salt-sensitive (DS) rats to test the hypothesis that hypertensive SS rats have increased cortical COX-2 upregulation, which is mediated by ANG II and ROS. DS rats were placed on either a normal-salt diet (0.5% NaCl) or a high-salt diet (4% NaCl) for 6 wk and treated with either the ANG II type 1 (AT1) receptor blocker candesartan (Can, 10 mg·kg−1·day−1) or the SOD mimetic tempol (1 mmol/l). Hypertensive SS rats had a twofold increase in the cortical expression of COX-2 as assessed by Western blot. These changes in COX-2 expression were accompanied by a 10-fold increase in COX-2 mRNA expression and a 2-fold increase in the urinary excretion of PGE2. Treatment with either the AT1receptor blocker Can or the SOD mimetic tempol did not reduce blood pressure but resulted in significant reductions in the cortical expression of COX-2 and the urinary excretion of PGE2. In conclusion, we have demonstrated that local activation of the renin-angiotensin system, via increased ROS generation, mediates COX-2 upregulation in hypertensive SS rats. These studies unveil novel mechanistic pathways that may play a role in the pathogenesis of hypertensive renal injury.

Thrombocytopenia and hemolytic anemia have been seen with thrombotic thrombocytopenic purpura (TTP), HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets), and hemolytic uremic syndrome (HUS). Differentiating between TTP, HUS, and HELLP syndrome is often difficult. Coexistence of TTP and HELLP is possible. Cardiomyopathy occurring in pregnancy can be idiopathic or associated with TTP. We describe a previously healthy woman who developed thrombocytopenia and hemolysis at 34 wk gestation. The patient underwent delivery after transfusion with platelets and RBCs. The suspicion of TTP was raised, and plasma exchange was begun by the third hospital day. On the seventh day of treatment, the patient developed shortness of breath, and an echocardiogram showed global hypokinesis with an ejection fraction of 25%. Plasma infusion, one unit q 4 h, was initiated in addition to the daily plasma exchange. The patient improved and her ejection fraction normalized. Plasma exchange and infusion and corticosteroids were gradually tapered off. von Willebrand factor (vWF) protease activity in the plasma upon transfer was completely deficient with the presence of inhibitor. This case illustrates that vWF protease assay and detection of inhibitor can be used for the diagnosis of TTP during pregnancy; and a severe cardiomyopathy in TTP can be reversed rapidly with combined plasma exchange and infusion.

Maladaptive activation of the renin-angiotensin system (RAS) has been shown to play a critical role in the pathogenesis of chronic kidney disease. Reactive oxygen species (ROS) are critical signals for many of the nonhemodynamic effects of angiotensin II (ANG II). We have demonstrated that ANG II increases mesangial and cortical cyclooxygenase-2 (COX-2) expression and activity via NADPH oxidase-derived ROS. The transcription factor ETS-1 (E26 transformation-specific sequence) has been identified as a critical regulator of growth-related responses and inflammation. The present studies were designed to determine: 1) whether ANG II induces ETS-1 expression in vitro in cultured rat mesangial cells and in vivo in rats infused with ANG II; and 2) whether ROS and COX-2 are mediators of ETS-1 induction in response to ANG II. Mesangial cells stimulated with ANG II (10−7M) exhibited a significant increase in ETS-1 expression that was prevented by the angiotensin type 1 receptor blocker candesartan. NADPH oxidase inhibition with dyphenilene iodinium or apocynin also prevented ETS-1 induction, establishing the role of ROS as mediators of ETS-1 expression in response to ANG II. COX-2 inhibition prevented ETS-1 expression in response to ANG II, suggesting that COX-2 is required for ETS-1 induction. By utilizing short interfering RNAs against ETS-1, we have also determined that ETS-1 is required to induce the production of fibronectin in response to ANG II. Furthermore, rats infused with ANG II manifested increased glomerular expression of ETS-1. These studies unveil novel pathways that may play an important role in the pathogenesis of renal injury when RAS is activated.

Normal expression and function of transfer RNA (tRNA) are of paramount importance for translation. In this study, we show that tRNA defects are also associated with increased levels of immature ribosomal RNA (rRNA). This association was first shown in detail for a mutant strain that underproduces tRNAArg2 in which unprocessed 16S and 23S rRNA levels were increased several-fold. Ribosome profiles indicated that unprocessed 23S rRNA in the mutant strain accumulates in ribosomal fractions that sediment with altered mobility. Underproduction of tRNAArg2 also resulted in growth defects under standard laboratory growth conditions. Interestingly, the growth and rRNA processing defects were attenuated when cells were grown in minimal medium or at low temperatures, indicating that the requirement for tRNAArg2 may be reduced under conditions of slower growth. Other tRNA defects were also studied, including a defect in RNase P, an enzyme involved in tRNA processing; a mutation in tRNATrp that results in its degradation at elevated temperatures; and the titration of the tRNA that recognizes rare AGA codons. In all cases, the levels of unprocessed 16S and 23S rRNA were enhanced. Thus, a range of tRNA defects can indirectly influence translation via effects on the biogenesis of the translation apparatus.

Thrombocytopenia and hemolytic anemia have been seen with thrombotic thrombocytopenic purpura (TTP), HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets), and hemolytic uremic syndrome (HUS). Differentiating between TTP, HUS, and HELLP syndrome is often difficult. Coexistence of TTP and HELLP is possible. Cardiomyopathy occurring in pregnancy can be idiopathic or associated with TTP. We describe a previously healthy woman who developed thrombocytopenia and hemolysis at 34 wk gestation. The patient underwent delivery after transfusion with platelets and RBCs. The suspicion of TTP was raised, and plasma exchange was begun by the third hospital day. On the seventh day of treatment, the patient developed shortness of breath, and an echocardiogram showed global hypokinesis with an ejection fraction of 25%. Plasma infusion, one unit q 4 h, was initiated in addition to the daily plasma exchange. The patient improved and her ejection fraction normalized. Plasma exchange and infusion and corticosteroids were gradually tapered off. von Willebrand factor (vWF) protease activity in the plasma upon transfer was completely deficient with the presence of inhibitor. This case illustrates that vWF protease assay and detection of inhibitor can be used for the diagnosis of TTP during pregnancy; and a severe cardiomyopathy in TTP can be reversed rapidly with combined plasma exchange and infusion.

Microglia (MG) are the resident immune cells of the CNS and are implicated as both important sensors for biological defense as well as mediators of various pathological conditions through the various inflammatory and oxidative molecules they produce. In the current study we compared different techniques for gene targeting of microglia using non-viral and viral methods in vitro for eventual application to the in vivo setting. For this investigation we employed the EOC2 MG cell line and three methods of gene introduction for pmax plasmid-GFP: electroporation,cationic lipid co-delivery andlentiviral vector infection. Electroporation when employed with various buffers and at different voltages led to low transfection efficacies (>1%). Transfection with cationic lipids (LipofectAmine, NovaFector, GeneFector) showed higher transfection rates (%), but these were still relatively low. In contrast, lentiviral vector delivery produced robust infection (>95%) and GFP expression. In addition, the activation of the cells, so that they underwent morphological (rounded) and immunophenotypical (ED1 immunoreactivity) changes, prior to or during transfection with the lower efficiency methods, did dramatically enhance efficiency (>95%). We conclude, that in CNS pathologies, where MG cells are activated, both non-viral and viral methods of gene therapy will likely be highly successful for the introduction of specific anti-inflammatory or immune suppressive genes. FUNDING: The Miami Project to Cure Paralysis, The Buoniconti Fund, The US Army Medical Research and Material Command

The adeno-associated virus (AAV) rep gene encodes a series of overlapping, multifunctional, nonstructural proteins (Rep proteins) which regulate the viral life cycle and which are also capable of trans-regulating nonviral gene expressions (reviewed in Berns, 1990 , Microbiol. Rev. 54, 316–329). To investigate the expression of the AAV rep gene in a cellular chromosomal context, SV40-transformed Chinese hamster embryo (OD4) cells were infected with an AAV/neo hybrid virus and progeny resistant to the antibiotic G418 were selected and amplified. Chromosomal integration and RNA transcription of the AAV and neo DNA inserts were confirmed by Southern and Northern blotting procedures. One of the G418R cell lines stably expressed a protein which reacted specifically with AAV anti-Rep antiserum in Western immunoblots. The stable integration of AAV rep DNA, which did not interfere with cell proliferation under normal growth conditions, was associated with two changes in cellular phenotype: eight of nine lines were markedly more sensitive to UV light (254 nm) than were the parental OD4 cells; and seven of the nine lines had lost the capacity to promote SV40 origin DNA amplification in vitro, in contrast to the parental OD4 cells. OD4 cells transformed to G418R by AAV/neo DNA constructs with a deleted rep gene, or by a neo DNA construct lacking AAV DNA, did not display these phenotypic changes. It is suggested that stable integration of the AAV rep gene interferes with cellular processes connected with DNA repair and gene amplification.