TLR4 (toll-like receptor 4) activation suppresses autophagy through inhibition of FOXO3 and impairs phagocytic capacity of microglia

Macroautophagy/autophagy is a lysosome-dependent catabolic process for the turnover of proteins and organelles in eukaryotes. Autophagy plays an important role in immunity and inflammation, as well as metabolism and cell survival. Diverse immune and inflammatory signals induce autophagy in macrophages through pattern recognition receptors, such as toll-like receptors (TLRs). However, the physiological role of autophagy and its signaling mechanisms in microglia remain poorly understood. Microglia are phagocytic immune cells that are resident in the central nervous system and share many characteristics with macrophages. Here, we show that autophagic flux and expression of autophagy-related (Atg) genes in microglia are significantly suppressed upon TLR4 activation by lipopolysaccharide (LPS), in contrast to their stimulation by LPS in macrophages. Metabolomics analysis of the levels of phosphatidylinositol (PtdIns) and its 3-phosphorylated form, PtdIns3P, in combination with bioinformatics prediction, revealed an LPS-induced reduction in the synthesis of PtdIns and PtdIns3P in microglia but not macrophages. Interestingly, inhibition of PI3K, but not MTOR or MAPK1/3, restored autophagic flux with concomitant dephosphorylation and nuclear translocation of FOXO3. A constitutively active form of FOXO3 also induced autophagy, suggesting FOXO3 as a downstream target of the PI3K pathway for autophagy inhibition. LPS treatment impaired phagocytic capacity of microglia, including MAP1LC3B/LC3-associated phagocytosis (LAP) and amyloid β (Aβ) clearance. PI3K inhibition restored LAP and degradation capacity of microglia against Aβ. These findings suggest a unique mechanism for the regulation of microglial autophagy and point to the PI3K-FOXO3 pathway as a potential therapeutic target to regulate microglial function in brain disorders. Abbreviations: Atg: autophagy-related gene; Aβ: amyloid-β; BafA1: bafilomycin A₁; BECN1: beclin 1, autophagy related; BMDM: bone marrow-derived macrophage; CA: constitutively active; CNS: central nervous system; ZFYVE1/DFCP1: zinc finger, FYVE domain containing 1; FOXO: forkhead box O; ELISA:enzyme-linked immunosorbent assay; HBSS: Hanks balanced salt solution; LAP: LC3-associated phagocytosis; MAP1LC3B: microtubule-associated protein 1 light chain 3; LPS: lipopolysaccharide; LY: LY294002; MTOR: mechanistic target of rapamycin kinase; Pam₃CSK₄: N-palmitoyl-S-dipalmitoylglyceryl Cys-Ser-(Lys)₄; PtdIns: phosphatidylinositol; PtdIns3P: phosphatidylinositol-3-phosphate; PLA: proximity ligation assay; Poly(I:C): polyinosinic-polycytidylic acid; qRT-PCR: quantitative real-time polymerase chain reaction; RPS6KB1: ribosomal protein S6 kinase, polypeptide 1; TLR: Toll-like receptor; TNF: tumor necrosis factor; TFEB: transcription factor EB; TSPO: translocator protein.

Use of personal protective equipment and operating room behaviors in four surgical subspecialties: personal protective equipment and behaviors in surgery

OBJECTIVE

To evaluate Universal Precautions (UP) compliance in the operating room (OR).

DESIGN

Prospective observational cohort. Trained observers recorded information about (1) personal protective equipment used by OR staff; (2) eyewear, glove, or gown breaks; (3) the nature of sharps transfers; (4) risk-taking behaviors of the OR staff; and (5) needlestick injuries and other blood and body-fluid exposures.

SETTING

Barnes-Jewish Hospital, a 1,000-bed, tertiary-care hospital affiliated with Washington University School of Medicine, St Louis, Missouri.

PARTICIPANTS

OR personnel in four surgical specialties (gynecologic, orthopedic, cardiothoracic, and general). Procedures eligible for the study were selected randomly. Hand surgery and procedures requiring no or a very small incision (eg, arthroscopy, laparoscopy) were excluded.

RESULTS

A total of 597 healthcare workers' procedures were observed in 76 surgical cases (200 hours). Of the 597 healthcare workers, 32% wore regular glasses, and 24% used no eye protection. Scrub nurses and medical students were more likely than other healthcare workers to wear goggles. Only 28% of healthcare workers double gloved, with orthopedic surgery personnel being the most compliant. Sharps passages were not announced in 91% of the surgical procedures. In 65 cases (86%), sharps were adjusted manually. Three percutaneous and 14 cutaneous exposures occurred, for a total exposure rate of 22%.

CONCLUSION

OR personnel had poor compliance with UP. Although there was significant variation in use of personal protective equipment between groups, the total exposure rate was high (22%), indicating the need for further training and reinforcement of UP to reduce occupational exposures.

Compliance with Universal Precautions among emergency department personnel: implications for prevention programs

BACKGROUND

We developed a 50-item questionnaire to assess emergency department (ED) staff members' knowledge of bloodborne pathogen transmission, compliance with Universal Precautions, and the use of personal protective equipment.

METHOD

A questionnaire was administered to 103 ED staff members including physicians, nurses, and technicians at Barnes-Jewish Hospital in St Louis, a Level-I trauma center.

RESULTS

ED personnel had inadequate knowledge of bloodborne pathogen infection risk, underreported exposures, and underused personal protection equipment during trauma cases.

CONCLUSION

Further educational interventions for ED personnel are needed to increase their compliance with Universal Precautions.

Improved compliance with universal precautions in the operating room following an educational intervention

Observation of surgical personnel in four specialties (cardiothoracic, general, gynecologic, and orthopedic) in the operating room was performed prior to implementation of an educational intervention designed to improve compliance with Universal Precautions and at 1- and 2-years post-intervention. Use of protective eyewear and double gloving increased following the intervention, whereas the incidence of documented blood and body fluid exposures decreased.

Evaluation of a preclinical, educational and skills-training program to improve students' use of blood and body fluid precautions: one-year follow-up

BACKGROUND

Little is known about long-term improvements in medical students' knowledge, attitudes, and use of blood and body fluid precautions following preclinical training.

METHODS

We evaluated an educational and skills-training program emphasizing double gloving for high-risk surgical procedures. Baseline surveys measuring knowledge, attitudes, and readiness to use specific precautions were completed by second-year (experimental) students before skills training and by third-year students (control) after their first clinical year. Follow-up surveys were completed 1 year later. Use of double gloves and protective eyewear during surgery clerkships was observed at baseline and follow-up.

RESULTS

Of 149 students returning both surveys, the experimental group (n = 91) showed improvements in attitudes toward double gloving (P = 0.038) and use of double gloves during surgery at follow-up (relative risk = 1.95, 95% confidence interval = 1.06, 3.59). They expressed better attitudes toward (P = 0.003) and greater readiness to use (P = 0. 020) double gloves compared with controls at follow-up. They expressed better attitudes toward (P = 0.002) and greater readiness to use (P = 0.001) double gloves compared with controls when each had completed their first clinical year.

CONCLUSION

The intervention was associated with improved attitudes toward and use of double gloves during surgery. The experimental group also expressed better attitudes and readiness to use double gloves compared with controls at follow-up.

Healthcare workers' attitudes and compliance with universal precautions: gender, occupation, and specialty differences

We describe variations in healthcare workers' attitudes toward double gloving and reporting needlesticks, and in their readiness to comply with double gloving and hepatitis B vaccine. Differences related to occupation, specialty, and gender have implications for the need to tailor interventions for specific groups of healthcare workers to improve compliance with Universal Precautions.

Histamine H3 agonist decreases arterial blood pressure in the guinea-pig

Intravenous injection of an H3-agonist, (R)-alpha-methylhistamine, dose-dependently caused a transient fall in mean arterial pressure of guinea-pigs. This pressor response was not reduced by combined mepyramine/cimetidine (up to 1 mg kg-1), atropine or propranolol, but was attenuated by either a selective H3-antagonist, thioperamide, or a competitive inhibitor of nitric oxide synthesis, NG-monomethyl L-arginine. The reduction by the inhibitor of nitric oxide synthesis was reversed by L- but not D-arginine. Histamine activated the H3-sites since its depressor response (obtained with mepyramine and cimetidine) was similar to that of (R)-alpha-methylhistamine. Our data indicate that H3-sites could exist in the cardiovascular system of guinea-pigs and that their stimulation might be mediated through the L-arginine/nitric oxide pathway.

Association of Protein Z with Prediabetes and Type 2 Diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a progressive metabolic disease. Early detection of prediabetes is important to reduce the risk of T2DM. Some cytokines are known to be associated with T2DM. Therefore, we aimed to identify cytokines as novel biomarkers of glucose dysmetabolism.

METHODS

The first stage of the study included 43 subjects (13 subjects with newly diagnosed T2DM, 13 with prediabetes, and 16 with normoglycemia) for cytokine microarray analysis. Blood samples of the subjects were assessed for 310 cytokines to identify potential indicators of prediabetes. The second stage included 142 subjects (36 subjects with T2DM, 35 with prediabetes, and 71 with normoglycemia) to validate the potential cytokines associated with prediabetes.

RESULTS

We identified 41 cytokines that differed by 1.5-fold or more in at least one out of the three comparisons (normoglycemia vs. prediabetes, normoglycemia vs. T2DM, and prediabetes vs. T2DM) among 310 cytokines. Finally, we selected protein Z (PROZ) and validated this finding to determine its association with prediabetes. Plasma PROZ levels were found to be decreased in patients with prediabetes (1,490.32±367.19 pg/mL) and T2DM (1,583.34±465.43 pg/mL) compared to those in subjects with normoglycemia (1,864.07±450.83 pg/mL) (P<0.001). There were significantly negative correlations between PROZ and fasting plasma glucose (P=0.001) and hemoglobin A1c (P=0.010).

CONCLUSION

PROZ levels were associated with prediabetes and T2DM. We suggest that PROZ may be a promising biomarker for the early detection of prediabetes. Further large-scale studies are needed to evaluate the relationship and mechanism between PROZ and prediabetes and T2DM.

Does clinical experience affect medical students' knowledge, attitudes, and compliance with universal precautions?

OBJECTIVE

To investigate differences in second-, third-, and fourth-year medical students' knowledge of bloodborne pathogen exposure risks, as well as their attitudes toward, and intentions to comply with, Universal Precautions (UP).

DESIGN

Cross-sectional survey.

PARTICIPANTS AND SETTING

Surveys about students' knowledge, attitudes, and intentions to comply with UP were completed by 111 second-year (preclinical), 80 third-year, and 60 fourth-year medical students at Washington University School of Medicine in the spring of 1996.

RESULTS

Preclinical students knew more than clinical students about the efficacy of hepatitis B vaccine, use of antiretroviral therapy after occupational exposure to human immunodeficiency virus, and nonvaccinated healthcare workers' risk of infection from needlestick injuries (P<.001). Students' perceived risk of occupational exposure to bloodborne pathogens and attitudes toward hepatitis B vaccine did not differ, but preclinical students agreed more strongly that they should double glove for all invasive procedures with sharps (P<.001). Clinical students agreed more strongly with reporting only high-risk needlestick injuries (P=.057) and with rationalizations against using UP (P=.008). Preclinical students more frequently reported contemplating or preparing to comply with double gloving, wearing protective eyewear, reporting all exposures, and safely disposing of sharps, whereas students with clinical experience were more likely to report compliance. Clinical students also were more likely to report having "no plans" to practice the first three of these precautions (P<.001).

CONCLUSIONS

Differences in knowledge, attitudes, and intentions to comply with UP between students with and without clinical experience may have important implications for the timing and content of interventions designed to improve compliance with UP.

Participation of vascular H1-receptors in histaminergic relaxation of rabbit middle cerebral artery in vitro

4-Methylhistamine relaxed potassium-constricted perfused rabbit middle cerebral arteries at low concentrations (3 X 10(-11) - 3 X 10(-8) M) and constricted them at high concentrations (3 X 10(-7) - 10(-4) M). The relaxation was antagonized by either cimetidine (3 X 10(-7) or 10(-6) M) or mepyramine (3 X 10(-8) M) given 20 min before testing a series of increasing concentrations of 4-methylhistamine, whereas the constriction was slightly potentiated by cimetidine and reversed by mepyramine. The reduction of relaxation was enhanced by a combination of both blockers. These results suggest the involvement of both H1- and H2-receptors in the 4-methylhistamine-induced relaxation. When dimaprit was compared with 4-methylhistamine, it acted only as a relaxing agent, not as a constricting agent. The dimaprit-induced relaxation was antagonized by either cimetidine (3 X 10(-7) M) or mepyramine (3 X 10(-8) M). The inhibition of relaxation was enhanced with a combination of both blockers. This supports the hypothesis that the dimaprit-induced relaxation in the rabbit cerebral artery is also mediated through both H1- and H2-receptors. The H1-agonists 2-methylhistamine and 2-pyridyl ethylamine induced two kinds of responses: an initial relaxation at low concentrations which was reversed by mepyramine (3 X 10(-8) or 10(-6) M) but not by cimetidine (10(-6) or 10(-5) M); this relaxation was followed at higher concentrations by a vasoconstriction which was antagonized by mepyramine (3 X 10(-8), 3 X 10(-7) or 10(-6) M) but not by cimetidine (10(-6) or 10(-5) M). Relaxation by these agents therefore seems to involve the participation of H1-receptors. The pharmacological effects of the histaminergic agonists and antagonists used could be explained by assuming that a distinction exists in the rabbit middle cerebral artery between the receptors concerned in H1-mediated relaxation and H1-mediated constriction.