Delays in anti-hyperglycaemic therapy initiation and intensification are associated with cardiovascular events, hospitalizations for heart failure and all-cause mortality.

AIMS: The aims of this study were to assess the impact of delays in treatment intensification (TI) on cardiovascular events, heart failure, and all-cause mortality at typical stages of anti-hyperglycaemic therapy. MATERIALS AND METHODS: Using electronic health record data, we created three TI cohorts of diabetes patients who: 1) initiated metformin (MET) as their first anti-hyperglycaemic therapy; 2) added a sulfonylurea (SU) to MET; and 3) initiated insulin (INS) while using MET or SU, alone or in combination. Primary exposure variables were haemoglobin A1C value preceding cohort therapy (pre-TI A1C) and time to intensification, that is, the time between pre-TI A1C >7% and cohort index date. Cox regression models were used to analyse the associated risk of cardiovascular events, hospitalizations for heart failure and all-cause mortality. RESULTS: In the MET cohort, each additional percentage point of pre-TI A1C was associated with a 10% increased risk of a CV event (HR, 1.10; 95% CI, 1.03-1.07; P = 0.004), a 7% increased risk of HF hospitalization (HR, 1.07; 95% CI, 1.01-1.14; P = 0.034) and a 7% increased risk of all-cause mortality (HR, 1.07; 95% CI, 1.01-1.14; P = 0.032). Pre-TI A1C was associated with a 9% increased risk of a CV event in the INS cohort (HR,1.09; 95% CI, 1.04-1.13; P < 0.001). Each month of delay in TI was significantly associated with a 6% increased risk of hospitalization for HF (HR, 1.06; 95% CI, 1.00-1.13; P = 0.040) and all-cause mortality (HR, 1.06; 95% CI, 1.00-1.13; P = 0.050) in the MET cohort. CONCLUSIONS: Delays in TI were associated with poor outcomes over a mean follow-up period of nearly five years. Earlier initiation and more rapid intensification of pharmacotherapy could reduce the risk of poor outcomes.

Longitudinal changes in glycated haemoglobin following treatment intensification after inadequate response to two oral antidiabetic agents in patients with type 2 diabetes.

AIMS: To identify change in glycated haemoglobin (HbA1c) for 1 year after treatment intensification in patients with HbA1c >53 mmol/mol (7.0%) while on two classes of oral antidiabetic drugs (OADs). MATERIAL AND METHODS: A retrospective cohort study was conducted using a regional health plan claims database for the period January 1, 2010 to March 31, 2017. Patients with type 2 diabetes (T2DM) whose treatment was intensified with insulin, a glucagon-like peptide-1 receptor agonist or a third OAD within 365 days of having HbA1c ≥53 mmol/mol (7.0%) on two OADs were included. The HbA1c trajectory for 1 year after intensification was estimated using a mixed-effects regression model. RESULTS: The analysis included 1226 patients with a mean ± SD HbA1c at treatment intensification of 74.2 ± 18.7 mmol/mol (8.93 ± 1.7%). HbA1c was higher in the insulin group (74.2 mmol/mol) than in the non-insulin group (70.6 mmol/mol), as was the HbA1c decrease (P < 0.01) over the 1-year follow-up, particularly in patients with baseline HbA1c >9%. After intensification, insulin- and non-insulin-treated patients achieved an average change by month in HbA1c of -4.7 mmol/mol and -2.6 mmol/mol points, respectively. The analysis predicted HbA1c to be the lowest at 6 to 10 months post intensification, depending on intensification treatment and HbA1c at intensification; however, on average, HbA1c remained above 64.0 mmol/mol (8.0%). CONCLUSION: In patients with T2DM, intensification following an HbA1c value ≥53 mmol/mol (7.0%) while on two OADs was associated with a significant improvement in glycaemic control. Patients intensified with insulin had a higher baseline HbA1c but greater HbA1c reduction than those intensified with a non-insulin agent. However, HbA1c remained above 64 mmol/mol (8.0%) overall. Additional opportunity exists to further intensify therapy to improve glycaemic control.

Factors Related to Biologic Adherence and Outcomes Among Moderate-to-Severe Asthma Patients.

BACKGROUND: Adherence barriers to asthma biologics may not be uniform across administration settings for patients with moderate-to-severe asthma. OBJECTIVE: To examine differences in asthma biologic adherence and associated factors, as well as association with a 1-year all-cause emergency department (ED) visit, across administration settings. METHODS: A retrospective study of biologic naïve moderate-to-severe asthma patients with initial biologic therapy between January 1, 2016, and April 30, 2020, in the Optum Clinformatics Data Mart was performed. Three administration settings were identified: Clinic-only (outpatient office/infusion center), Home (self-administration), and Hybrid setting (mixture of clinic and self-administration). Asthma biologic adherence was the proportion of observed over expected biologic dose administrations received within 6 months from initial therapy. Factors associated with adherence were identified by administration setting, using Poisson regression analyses. A relationship between a 1-year all-cause ED visit and adherence was assessed for each administration setting using Cox regression analyses. RESULTS: The study cohort was 3932 patients. Biologics adherence was 0.75 [0.5, 1] in Clinic setting, the most common administration setting, and 0.83 [0.5, 1] in both Home and Hybrid settings. Specialist access was consistently associated with better biologic adherence, whereas Black race, Hispanic ethnicity, lower education, Medicare only insurance, and higher patient out-of-pocket cost were associated with worse biologic adherence in some settings. In the Hybrid setting, hazard for a 1-year all-cause ED visit decreased with biologic adherence. CONCLUSIONS: Asthma biologic adherence varied by administration setting. Efforts to improve asthma biologic adherence should consider promoting self-administration when beneficial, improving prior specialist access, and targeting patients with higher risk of suboptimal adherence particularly Black and Hispanic patients.

An Shp2/SFK/Ras/Erk signaling pathway controls trophoblast stem cell survival.

Little is known about how growth factors control tissue stem cell survival and proliferation. We analyzed mice with a null mutation of Shp2 (Ptpn11), a key component of receptor tyrosine kinase signaling. Null embryos die peri-implantation, much earlier than mice that express an Shp2 truncation. Shp2 null blastocysts initially develop normally, but they subsequently exhibit inner cell mass death, diminished numbers of trophoblast giant cells, and failure to yield trophoblast stem (TS) cell lines. Molecular markers reveal that the trophoblast lineage, which requires fibroblast growth factor-4 (FGF4), is specified but fails to expand normally. Moreover, deletion of Shp2 in TS cells causes rapid apoptosis. We show that Shp2 is required for FGF4-evoked activation of the Src/Ras/Erk pathway that culminates in phosphorylation and destabilization of the proapoptotic protein Bim. Bim depletion substantially blocks apoptosis and significantly restores Shp2 null TS cell proliferation, thereby establishing a key mechanism by which FGF4 controls stem cell survival.

FAK-Src signalling through paxillin, ERK and MLCK regulates adhesion disassembly.

Cell migration is a complex, highly regulated process that involves the continuous formation and disassembly of adhesions (adhesion turnover). Adhesion formation takes place at the leading edge of protrusions, whereas disassembly occurs both at the cell rear and at the base of protrusions. Despite the importance of these processes in migration, the mechanisms that regulate adhesion formation and disassembly remain largely unknown. Here we develop quantitative assays to measure the rate of incorporation of molecules into adhesions and the departure of these proteins from adhesions. Using these assays, we show that kinases and adaptor molecules, including focal adhesion kinase (FAK), Src, p130CAS, paxillin, extracellular signal-regulated kinase (ERK) and myosin light-chain kinase (MLCK) are critical for adhesion turnover at the cell front, a process central to migration.

Therapeutic Inertia in Prescribing Biologics for Patients with Moderate-to-Severe Asthma: Workshop Summary.

Moderate-to-severe asthma represents about a quarter of the nearly 10% of Americans diagnosed with asthma. Many patients with moderate-to-severe asthma have uncontrolled symptoms that lead to exacerbations requiring oral corticosteroids. There are many factors contributing to poor asthma control, including poor adherence to prescribed therapies, the under-prescribing of biologics and therapeutic inertia. We convened an eight-member panel from fields of primary care, pulmonology, immunology, health services and clinical research, behavioral science and pharmaceutical medical affairs, with the goal of identifying contributing factors and solutions to therapeutic inertia with asthma biologics. We used the Capability, Opportunity, and Motivation (COM-B) model to classify patient and provider behavior towards therapeutic inertia. The model incorporates existing behavior theories and is driven by the interaction of capability, opportunity, and motivation. We used a Delphi method to identify and develop six primary solutions: 1) integration of patient-centered outcomes into asthma management practice; 2) provider education about asthma treatment; 3) moderate-to-severe asthma care delivery redesign; 4) harmonized, evidence-based protocol for the management of moderate-to-severe asthma; 5) designated coordinator approach for optimal asthma management; and 6) a case coordination digital support tool. Integration of patient-centered outcomes into asthma management practice and provider education were identified as having the highest potential to impact therapeutic and clinical inertia. The COM-B model is effective in identifying improvement within therapeutic inertia targeting the capabilities, opportunities, and motivations of patients, providers, and payer systems.

Statin Therapy and Risk of Incident Diabetes Mellitus in Adults With Cardiovascular Risk Factors.

The association between statins and diabetes mellitus (DM) remains controversial. The Kaiser Permanente CHAMP Study identified adults without DM who had cardiovascular (CV) risk factors and no previous lipid lowering therapy (LLT) between 2008 and 2010. The CV risk factors included known atherosclerotic CV disease (ASCVD), elevated low-density lipoprotein cholesterol ≥190 mg/dl, or a low-density lipoprotein cholesterol between 70 and 189 mg/dl and an estimated 10-year ASCVD risk ≥7.5%. Incident DM was defined as ≥2 abnormal tests (i.e., A1C ≥6.5% or a fasting blood glucose ≥126 mg/dl) or ≥1 abnormal test result plus a new diagnostic code or medication for DM. Among 213,289 eligible adults, 28,149 patients initiating statins were carefully matched to an equal number of patients who remained off LLT during follow-up. Compared with matched patients not receiving statins, those initiating statin therapy had the same mean age (67.9 ± 9.4 years) and gender (42.8% women). The crude rate (per 100 person-years) of incident DM was low (0.55, 95% confidence interval [CI] 0.52 to 0.59) but was marginally higher in patients who were treated with a statin (0.69, 95% CI 0.64 to 0.74) versus no LLT (0.42, 95% CI 0.38 to 0.46). After additional adjustment, statin therapy was associated with a modestly increased risk of incident DM (adjusted hazard ratio 1.17, 95% CI 1.02 to 1.34). In conclusion, in adults without DM at increased ASCVD risk, initiation of statin therapy was independently associated with a modestly higher risk of incident DM.

Influence of Treatment Intensification on A1c in Patients with Suboptimally Controlled Type 2 Diabetes After 2 Oral Antidiabetic Agents.

BACKGROUND: In the United States, more than 50% of patients with type 2 diabetes mellitus (T2DM) have hemoglobin A1c (A1c) levels that fail to achieve the recommended target of < 7.0%. Of these, 30%-45% have an A1c > 9.0%, the threshold for poorly controlled T2DM per National Committee for Quality Assurance (NCQA) measures. Treatment inertia is a known challenge. However, recent treatment intensification patterns and outcomes after treatment fails 2 classes of oral antidiabetic agents (OADs) are not well understood. OBJECTIVE: To characterize treatment intensification patterns and glycemic control outcomes in patients with A1c ≥ 7.0% on 2 OADs. METHODS: A retrospective cohort study was conducted in patients with T2DM from a regional health plan claims dataset augmented with A1c results between January 1, 2010, and March 31, 2017. Patients were identified with an A1c ≥ 7.0% (baseline), while on 2 OADs, and whose treatment was intensified with basal/biphasic insulin (insulin), glucagon-like peptide-1 receptor antagonist (GLP-1RA), or a third OAD within 365 days after the baseline A1c ≥ 7.0%. Patients had at least 1 A1c value 60-365 days (follow-up period) after treatment intensification. The proportion of patients with an A1c < 7.0% and < 9.0% at follow-up were identified by therapeutic intensification strategy. Odds ratios for achieving A1c < 7.0% and < 9.0% were calculated. RESULTS: 1,226 patients were included in the analysis, and 33.5% of the patients had a baseline A1c ≥ 9.0%. 24% of patients received insulin; 16% received GLP-1RA; and 60% received a third OAD for the treatment intensification. Overall, 26.0% achieved A1c < 7.0% and 76.1% of patients achieved < 9.0%, with a median follow-up of 119 days. The proportion of patients intensified with insulin who had an A1c ≥ 9.0% at follow-up was 34.6% versus 53.2% at baseline (P < 0.01). The corresponding percentages for those intensified with a GLP-1RA and OAD were 21.6% versus 27.1% (P = 0.24) and 20.1% versus 27.3% (P < 0.01). After controlling for baseline characteristics, the odds ratio (95% CI) of achieving A1c < 7.0% and < 9.0% was 2.05 (1.45-2.90) for GLP-1RA and 0.92 (0.61-1.40) for OAD. The association between goal attainment and GLP-1RA versus OAD intensification was influenced by the time to the A1c follow-up and baseline A1c. CONCLUSIONS: Treatment intensification was associated with improved glycemic control in patients after therapy failed 2 OADs. Patients with higher A1c at baseline were likely to initiate insulin, which was associated with a greater drop in A1c. GLP-1RA was associated with a higher likelihood of achieving NCQA-suggested glycemic control compared with a third OAD. However, the association varied by the follow-up period. These findings are important to health plans seeking to improve patient outcomes as reflected in high performance on NCQA diabetes quality measures by promoting effective and timely treatment intensification. DISCLOSURES: Research funding was provided by Sanofi to the Pharmacotherapy Outcomes Research Center at the University of Utah and SelectHealth to conduct this study. Thomas, Sterling, and Johnstone are employees and stock/shareholders of Sanofi. Kim, Unni, McAdam-Marx, and Brixner are employees of the Department of Pharmacotherapy at the University of Utah. Brixner also has served as an advisory board member and presenter for Sanofi. McAdam-Marx also reports grants to the Department of Pharmacotherapy, University of Utah, from AstraZeneca and Janssen, outside of the submitted work. Olsen is employed by SelectHealth. Part of the results of this study was presented at the Academy of Managed Care & Specialty Pharmacy Annual Meeting 2018 in Boston, MA, during April 23-26, 2018.

Endothelial cell cortactin phosphorylation by Src contributes to polymorphonuclear leukocyte transmigration in vitro.

The underlying mechanisms that regulate leukocyte transendothelial migration through the vascular endothelium remain unclear. Cortactin is a substrate of Src tyrosine kinases and a regulator of cytoskeletal dynamics. Previous studies demonstrated a role for Src phosphorylation of cortactin in clustering of E-selectin and intercellular cell adhesion molecule-1 around adherent leukocytes. In the current study, we used an in vitro flow model to investigate the role of Src-induced cortactin phosphorylation in endothelium during polymorphonuclear leukocyte (PMN) transmigration through human umbilical vein endothelium (HUVEC) monolayers preactivated with tumor necrosis factor-alpha. Inhibition of Src in HUVEC using Src kinase inhibitors PP2 and SU6656 reduced PMN transmigration by 45+/-8% and 36+/-6%, respectively. Live cell imaging of green fluorescent protein-tagged cortactin in HUVEC revealed redistribution of cortactin in the region surrounding transmigrating PMN. Knockdown of cortactin in HUVEC by small interfering RNA also impaired transmigration to a similar degree, and this phenotype was rescued by reexpression of wild-type cortactin. Analysis of the location of initial arrest and locomotion of PMN adherent to HUVEC demonstrated that inhibition of Src tyrosine kinases or pretreatment with cortactin small interfering RNA reduced PMN transmigration at endothelial cell-to-cell junctions and not adhesion. Tyrosine phosphorylation of cortactin was important for transmigration, because expression of a mutant, in which the tyrosine phosphorylation sites were mutated to phenylalanine (cortactin3F), failed to rescue PMN transmigration. Moreover, expression of cortactin3F alone partially blocked PMN transmigration. These data suggest a model whereby tyrosine phosphorylation of cortactin by Src family kinases regulates PMN transmigration.

Regulation of Rho and Rac signaling to the actin cytoskeleton by paxillin during Drosophila development.

Paxillin is a prominent focal adhesion docking protein that regulates cell adhesion and migration. Although numerous paxillin-binding proteins have been identified and paxillin is required for normal embryogenesis, the precise mechanism by which paxillin functions in vivo has not yet been determined. We identified an ortholog of mammalian paxillin in Drosophila (Dpax) and have undertaken a genetic analysis of paxillin function during development. Overexpression of Dpax disrupted leg and wing development, suggesting a role for paxillin in imaginal disc morphogenesis. These defects may reflect a function for paxillin in regulation of Rho family GTPase signaling as paxillin interacts genetically with Rac and Rho in the developing eye. Moreover, a gain-of-function suppressor screen identified a genetic interaction between Dpax and cdi in wing development. cdi belongs to the cofilin kinase family, which includes the downstream Rho target, LIM kinase (LIMK). Significantly, strong genetic interactions were detected between Dpax and Dlimk, as well as downstream effectors of Dlimk. Supporting these genetic data, biochemical studies indicate that paxillin regulates Rac and Rho activity, positively regulating Rac and negatively regulating Rho. Taken together, these data indicate the importance of paxillin modulation of Rho family GTPases during development and identify the LIMK pathway as a critical target of paxillin-mediated Rho regulation.

Role of phosphoinositide 3-kinase regulatory isoforms in development and actin rearrangement.

Class Ia phosphoinositide 3-kinases (PI3Ks) are heterodimers of p110 catalytic and p85 regulatory subunits that mediate a variety of cellular responses to growth and differentiation factors. Although embryonic development is not impaired in mice lacking all isoforms of the p85alpha gene (p85alpha-/- p55alpha-/- p50alpha-/-) or in mice lacking the p85beta gene (p85beta-/-) (D. A. Fruman, F. Mauvais-Jarvis, D. A. Pollard, C. M. Yballe, D. Brazil, R. T. Bronson, C. R. Kahn, and L. C. Cantley, Nat Genet. 26:379-382, 2000; K. Ueki, C. M. Yballe, S. M. Brachmann, D. Vicent, J. M. Watt, C. R. Kahn, and L. C. Cantley, Proc. Natl. Acad. Sci. USA 99:419-424, 2002), we show here that loss of both genes results in lethality at embryonic day 12.5 (E12.5). The phenotypes of these embryos, including subepidermal blebs flanking the neural tube at E8 and bleeding into the blebs during the turning process, are similar to defects observed in platelet-derived growth factor receptor alpha null (PDGFRalpha-/-) mice (P. Soriano, Development 124:2691-2700, 1997), suggesting that PI3K is an essential mediator of PDGFRalpha signaling at this developmental stage. p85alpha-/- p55alpha+/+ p50alpha+/+ p85beta-/- mice had similar but less severe defects, indicating that p85alpha and p85beta have a critical and redundant function in development. Mouse embryo fibroblasts deficient in all p85alpha and p85beta gene products (p85alpha-/- p55alpha-/- p50alpha-/- p85beta-/-) are defective in PDGF-induced membrane ruffling. Overexpression of the Rac-specific GDP-GTP exchange factor Vav2 or reintroduction of p85alpha or p85beta rescues the membrane ruffling defect. Surprisingly, reintroduction of p50alpha also restored PDGF-dependent membrane ruffling. These results indicate that class Ia PI3K is critical for PDGF-dependent actin rearrangement but that the SH3 domain and the Rho/Rac/Cdc42-interacting domain of p85, which lacks p50alpha, are not required for this response.

RNF5, a RING finger protein that regulates cell motility by targeting paxillin ubiquitination and altered localization.

RNF5 is a RING finger protein found to be important in the growth and development of Caenorhabditis elegans. The search for RNF5-associated proteins via a yeast two-hybrid screen identified a LIM-containing protein in C. elegans which shows homology with human paxillin. Here we demonstrate that the human homologue of RNF5 associates with the amino-terminal domain of paxillin, resulting in its ubiquitination. RNF5 requires intact RING and C-terminal domains to mediate paxillin ubiquitination. Whereas RNF5 mediates efficient ubiquitination of paxillin in vivo, protein extracts were required for in vitro ubiquitination, suggesting that additional modifications and/or an associated E3 ligase assist RNF5 targeting of paxillin ubiquitination. Mutant Ubc13 efficiently inhibits RNF5 ubiquitination, suggesting that RNF5 generates polychain ubiquitin of the K63 topology. Expression of RNF5 increases the cytoplasmic distribution of paxillin while decreasing its localization within focal adhesions, where it is primarily seen under normal growth. Concomitantly, RNF5 expression results in inhibition of cell motility. Via targeting of paxillin ubiquitination, which alters its localization, RNF5 emerges as a novel regulator of cell motility.

The adaptor protein paxillin is essential for normal development in the mouse and is a critical transducer of fibronectin signaling.

The integrin family of cell adhesion receptors are important for a diverse set of biological responses during development. Although many integrins have been shown to engage a similar set of cytoplasmic effector proteins in vitro, the importance of these proteins in the biological events mediated by different integrin receptors and ligands is uncertain. We have examined the role of one of the best-characterized integrin effectors, the focal adhesion protein paxillin, by disruption of the paxillin gene in mice. Paxillin was found to be critically involved in regulating the development of mesodermally derived structures such as heart and somites. The phenotype of the paxillin(-/-) mice closely resembles that of fibronectin(-/-) mice, suggesting that paxillin is a critical transducer of signals from fibronectin receptors during early development. Paxillin was also found to play a critical role in fibronectin receptor biology ex vivo since cultured paxillin-null fibroblasts display abnormal focal adhesions, reduced cell migration, inefficient localization of focal adhesion kinase (FAK), and reduced fibronectin-induced phosphorylation of FAK, Cas, and mitogen-activated protein kinase. In addition, we found that paxillin-null fibroblasts show some defects in the cortical cytoskeleton and cell spreading on fibronectin, raising the possibility that paxillin could play a role in structures distinct from focal adhesions. Thus, paxillin and fibronectin regulate some common embryonic developmental events, possibly due to paxillin modulation of fibronectin-regulated focal adhesion dynamics and organization of the membrane cytoskeletal structures that regulate cell migration and spreading.

The multiple LIM domain-containing adaptor protein Hic-5 synaptically colocalizes and interacts with the dopamine transporter.

The Na+/Cl--dependent dopamine transporter (DAT) is critical in terminating dopaminergic transmission by removing the transmitter away from the synapse. Several lines of evidence suggest that transporter-interacting proteins may play a role in DAT function and regulation. In this report, using the yeast two-hybrid system, we have identified a novel interaction between DAT and the multiple Lin-11, Isl-1, and Mec-3 (LIM) domain-containing adaptor protein Hic-5. This association involves the N-terminal portion of the intracellular tail of DAT and the LIM region of Hic-5. In human embryonic kidney 293 cells, Hic-5 colocalizes with DAT at polarized sites and reduces DAT uptake activity through a mechanism involving a decrease in the cell-surface levels of the transporter. A fragment of Hic-5 containing the LIM domains is sufficient to bind DAT but lacks the ability to inhibit transporter activity. In addition, the LIM fragment prevents the effect of the full-length Hic-5 on DAT localization and function. In the brain, Hic-5 protein is expressed in the cerebral cortex, hippocampus, hypothalamus, cerebellum, and striatum, suggesting a role for this protein in the nervous system. The association of the endogenous Hic-5 and DAT proteins was confirmed biochemically by coimmunoprecipitation from brain striatal extracts. Moreover, immunostaining of rat midbrain neurons in culture revealed a presynaptic colocalization of Hic-5 and DAT. Because Hic-5 has been shown to interact with several signaling molecules, including the nonreceptor protein tyrosine kinases focal adhesion kinase and Fyn, this raises the possibility that this adaptor protein may link DAT to intracellular signaling pathways.

Impact of Clostridium difficile-associated diarrhea on acute care length of stay, hospital costs, and readmission: A multicenter retrospective study of inpatients, 2009-2011.

BACKGROUND: The recent epidemiologic changes of Clostridium difficile-associated diarrhea (CDAD) have resulted in substantial economic burden to U.S. acute care hospitals. Past studies evaluating CDAD-attributable costs have been geographically and demographically limited. Here, we describe CDAD-attributable burden in inpatients, overall, and in vulnerable subpopulations from the Premier hospital database, a large, diverse cohort with a wide range of high-risk subgroups. METHODS: Discharges from the Premier database were retrospectively analyzed to assess length of stay (LOS), total inpatient costs, readmission, and inpatient mortality. RESULTS: Patients with CDAD had significantly worse outcomes than matched controls in terms of total LOS, rates of intensive care unit (ICU) admission, and inpatient mortality. After adjustment for risk factors, patients with CDAD had increased odds of inpatient mortality, total and ICU LOS, costs, and odds of 30-, 60- and 90-day all-cause readmission versus non-CDAD patients. CDAD-attributable costs were higher in all studied vulnerable subpopulations, which also had increased odds of 30-, 60- and 90-day all-cause readmission than those without CDAD. CONCLUSION: Given the significant economic impact CDAD has on hospitals, prevention of initial episodes and targeted therapy to prevent recurrences in vulnerable patients are essential to decrease the overall burden to hospitals.

AMPK-dependent phosphorylation of ULK1 regulates ATG9 localization.

Autophagy is activated in response to a variety of cellular stresses including metabolic stress. While elegant genetic studies in yeast have identified the core autophagy machinery, the signaling pathways that regulate this process are less understood. AMPK is an energy sensing kinase and several studies have suggested that AMPK is required for autophagy. The biochemical connections between AMPK and autophagy, however, have not been elucidated. In this report, we identify a biochemical connection between a critical regulator of autophagy, ULK1, and the energy sensing kinase, AMPK. ULK1 forms a complex with AMPK, and AMPK activation results in ULK1 phosphorylation. Moreover, we demonstrate that the immediate effect of AMPK-dependent phosphorylation of ULK1 results in enhanced binding of the adaptor protein YWHAZ/14-3-3ζ; and this binding alters ULK1 phosphorylation in vitro. Finally, we provide evidence that both AMPK and ULK1 regulate localization of a critical component of the phagophore, ATG9, and that some of the AMPK phosphorylation sites on ULK1 are important for regulating ATG9 localization. Taken together these data identify an ULK1-AMPK signaling cassette involved in regulation of the autophagy machinery.

Inhibition of mammalian S6 kinase by resveratrol suppresses autophagy.

Resveratrol is a plant-derived polyphenol that promotes health and disease resistance in rodent models, and extends lifespan in lower organisms. A major challenge is to understand the biological processes and molecular pathways by which resveratrol induces these beneficial effects. Autophagy is a critical process by which cells turn over damaged components and maintain bioenergetic requirements. Disruption of the normal balance between pro- and anti-autophagic signals is linked to cancer, liver disease, and neurodegenerative disorders. Here we show that resveratrol attenuates autophagy in response to nutrient limitation or rapamycin in multiple cell lines through a pathway independent of a known target, SIRT1. In a large-scalein vitro kinase screen we identified p70 S6 kinase (S6K1) as a target of resveratrol. Blocking S6K1 activity by expression of a dominant-negative mutant or RNA interference is sufficient to disrupt autophagy to a similar extent as resveratrol. Furthermore, co-administration of resveratrol with S6K1 knockdown does not produce an additive effect. These data indicate that S6K1 is important for the full induction of autophagy in mammals and raise the possibility that some of the beneficial effects of resveratrol are due to modulation of S6K1 activity.

Genetic interactions between Drosophila melanogaster Atg1 and paxillin reveal a role for paxillin in autophagosome formation.

Autophagy is a conserved cellular process of macromolecule recycling that involves vesicle-mediated degradation of cytoplasmic components. Autophagy plays essential roles in normal cell homeostasis and development, the response to stresses such as nutrient starvation, and contributes to disease processes including cancer and neurodegeneration. Although many of the autophagy components identified from genetic screens in yeast are well conserved in higher organisms, the mechanisms by which this process is regulated in any species are just beginning to be elucidated. In a genetic screen in Drosophila melanogaster, we have identified a link between the focal adhesion protein paxillin and the Atg1 kinase, which has been previously implicated in autophagy. In mammalian cells, we find that paxillin is redistributed from focal adhesions during nutrient deprivation, and paxillin-deficient cells exhibit defects in autophagosome formation. Together, these findings reveal a novel evolutionarily conserved role for paxillin in autophagy.

Endothelial cell cortactin coordinates intercellular adhesion molecule-1 clustering and actin cytoskeleton remodeling during polymorphonuclear leukocyte adhesion and transmigration.

Endothelial cell ICAM-1 interacts with leukocyte beta(2) integrins to mediate adhesion and transmit outside-in signals that facilitate leukocyte transmigration. ICAM-1 redistribution and clustering appear necessary for leukocyte transmigration, but the mechanisms controlling ICAM-1 redistribution and clustering have not been identified. We recently reported that Src kinase phosphorylation of endothelial cortactin regulates polymorphonuclear cell (PMN) transmigration. In this study, we tested the hypotheses that the Src family kinase-cortactin pathway mediates association of ICAM-1 with the actin cytoskeleton and that this association is required for ICAM-1 clustering and leukocyte transmigration. Cross-linking ICAM-1 induced cytoskeletal remodeling and a decrease in ICAM-1 lateral mobility, as assessed by fluorescence recovery after photobleaching. Cytoskeletal remodeling after ICAM-1 cross-linking was reduced by knockdown of cortactin by small interfering RNA, by expression of a cortactin mutant deficient in Src phosphorylation sites (cortactin3F), and by the Src kinase inhibitor PP2. Pretreatment of cytokine-activated human endothelial monolayers with cortactin small interfering RNA significantly decreased both actin and ICAM-1 clustering around adherent PMN and the formation of actin-ICAM-1 clusters required for PMN transmigration. Our data suggest a model in which tyrosine phosphorylation of cortactin dynamically links ICAM-1 to the actin cytoskeleton, enabling ICAM-1 to form clusters and facilitate leukocyte transmigration.

Cortactin regulates cell migration through activation of N-WASP.

Cortactin is an actin-associated scaffolding protein that regulates cell migration. Amplification of the human gene, EMS1, has been detected in breast, head and neck tumors, where it correlates with increased invasiveness. Cortactin can regulate actin dynamics directly via its N-terminal half, which can bind and activate the Arp2/3 complex. The C-terminal portion of cortactin, however, is thought to have limited function in its regulation of the actin polymerization machinery. In this report, we identify a role for the cortactin C-terminus in regulating cell migration and, more specifically, actin dynamics. Overexpression of either full-length cortactin or cortactin C-terminus is sufficient to enhance migration of mammary epithelial cells. In vitro, cortactin binds to and activates, via its SH3 domain, a regulator of the Arp2/3 complex, neural Wiskott Aldrich Syndrome protein (N-WASP). This in vitro activation of N-WASP is likely to be important in vivo, as cortactin-enhanced migration is dependent upon N-WASP. Thus, our results suggest that cortactin has multiple mechanisms by which it can recruit and modulate the actin machinery and ultimately regulate cell migration.