Alzheimer's disease-related presenilins are key to intestinal epithelial cell function and gut immune homoeostasis.

OBJECTIVE: Mutations in presenilin genes are the major cause of Alzheimer's disease. However, little is known about their expression and function in the gut. In this study, we identify the presenilins Psen1 and Psen2 as key molecules that maintain intestinal homoeostasis. DESIGN: Human inflammatory bowel disease (IBD) and control samples were analysed for Psen1 expression. Newly generated intestinal epithelium-specific Psen1-deficient, Psen2-deficient and inducible Psen1/Psen2 double-deficient mice were used to dissect the functional role of presenilins in intestinal homoeostasis. RESULTS: Psen1 expression was regulated in experimental gut inflammation and in patients with IBD. Induced deletion of Psen1 and Psen2 in mice caused rapid weight loss and spontaneous development of intestinal inflammation. Mice exhibited epithelial barrier disruption with bacterial translocation and deregulation of key pathways for nutrient uptake. Wasting disease was independent of gut inflammation and dysbiosis, as depletion of microbiota rescued Psen-deficient animals from spontaneous colitis development but not from weight loss. On a molecular level, intestinal epithelial cells lacking Psen showed impaired Notch signalling and dysregulated epithelial differentiation. CONCLUSION: Overall, our study provides evidence that Psen1 and Psen2 are important guardians of intestinal homoeostasis and future targets for barrier-promoting therapeutic strategies in IBD.

Implementation of a Novel Prehospital Clinical Decision Tool and ECG Transmission for STEMI Significantly Reduces Door-to-Balloon Time and Sex-Based Disparities.

BACKGROUND: An important method employed to reduce door to balloon time (DTBT) for ST segment elevation Myocardial Infarctions (STEMIs) is a prehospital MI alert. The purpose of this retrospective study was to examine the effects of an educational intervention using a novel decision support method of STEMI notification and prehospital electrocardiogram (ECG) transmission on DTBT. METHODS: An ongoing database (April 4, 2000 - present) is maintained to track STEMI alerts. In 2007, an MI alert program began; emergency medicine physicians could activate a "prehospital MI alert". In October 2015, modems were purchased for Emergency Medical Services personnel to transmit ECGs. There was concurrent implementation of a decision support tool for identifying STEMI. Sex was assigned as indicated in the medical record. Data were analyzed in two groups: Pre-2016 (PRE) and 2016-2022 (POST). RESULTS: In total, 3,153 patients (1,301 PRE; 1,852 POST) were assessed; the average age was 65.2 years, 32.6% female, 87.7% white with significant differences in age and race between the two cohorts. Of the total 3,153 MI alerts, 239 were false activations, leaving 2,914 for analysis. 2,115 (72.6%) had cardiac catheterization while 16 (6.7%) of the 239 had a cardiac catheterization. There was an overall decrease in DTBT of 27.5% PRE to POST of prehospital ECG transmission (p < 0.001); PRE median time was 74.5 min vs. 55 min POST. There was no significant difference between rates of cardiac catheterization PRE and POST for all patients. After accounting for age, race, and mode of arrival, DTBT was 12.2% longer in women, as compared to men (p < 0.001) PRE vs. POST. DTBT among women was significantly shorter when comparing PRE to POST periods (median 77 min vs. 60 min; p = 0.0001). There was no significant sex difference in the proportion of those with cardiac catheterization between the two cohorts (62.5% vs. 63.5%; p = 0.73). CONCLUSION: Introduction of a decision support tool with prehospital ECG transmission with prehospital ECG transmission decreased overall DTBT by 20 min (27.5%). Women in the study had a 17-minute decrease in DTBT (22%), but their DTBT remained 12.2% longer than men for reasons that remain unclear.

Epithelial presenilin-1 drives colorectal tumour growth by controlling EGFR-COX2 signalling.

OBJECTIVE: Psen1 was previously characterised as a crucial factor in the pathogenesis of neurodegeneration in patients with Alzheimer's disease. Little, if any, is known about its function in the gut. Here, we uncovered an unexpected functional role of Psen1 in gut epithelial cells during intestinal tumourigenesis. DESIGN: Human colorectal cancer (CRC) and control samples were investigated for PSEN1 and proteins of theγ-secretase complex. Tumour formation was analysed in the AOM-DSS and Apc min/+ mouse models using newly generated epithelial-specific Psen1 deficient mice. Psen1 deficient human CRC cells were studied in a xenograft tumour model. Tumour-derived organoids were analysed for growth and RNA-Seq was performed to identify Psen1-regulated pathways. Tumouroids were generated to study EGFR activation and evaluation of the influence of prostanoids. RESULTS: PSEN1 is expressed in the intestinal epithelium and its level is increased in human CRC. Psen1-deficient mice developed only small tumours and human cancer cell lines deficient in Psen1 had a reduced tumourigenicity. Tumouroids derived from Psen1-deficient Apc min/+ mice exhibited stunted growth and reduced cell proliferation. On a molecular level, PSEN1 potentiated tumour cell proliferation via enhanced EGFR signalling and COX-2 production. Exogenous administration of PGE2 reversed the slow growth of PSEN1 deficient tumour cells via PGE2 receptor 4 (EP4) receptor signalling. CONCLUSIONS: Psen1 drives tumour development by increasing EGFR signalling via NOTCH1 processing, and by activating the COX-2-PGE2 pathway. PSEN1 inhibition could be a useful strategy in treatment of CRC.

Proteolytic Activity of the Paracaspase MALT1 Is Involved in Epithelial Restitution and Mucosal Healing.

The paracaspase MALT1 is a crucial regulator of immune responses in various cellular contexts. Recently, there is increasing evidence suggesting that MALT1 might represent a novel key player in mucosal inflammation. However, the molecular mechanisms underlying this process and the targeted cell population remain unclear. In this study, we investigate the role of MALT1 proteolytic activity in the context of mucosal inflammation. We demonstrate a significant enrichment of MALT1 gene and protein expression in colonic epithelial cells of UC patients, as well as in the context of experimental colitis. Mechanistically we demonstrate that MALT1 protease function inhibits ferroptosis, a form of iron-dependent cell death, upstream of NF-κB signaling, which can promote inflammation and tissue damage in IBD. We further show that MALT1 activity contributes to STAT3 signaling, which is essential for the regeneration of the intestinal epithelium after injury. In summary, our data strongly suggests that the protease function of MALT1 plays a critical role in the regulation of immune and inflammatory responses, as well as mucosal healing. Understanding the mechanisms by which MALT1 protease function regulates these processes may offer novel therapeutic targets for the treatment of IBD and other inflammatory diseases.

Neutrophils prevent rectal bleeding in ulcerative colitis by peptidyl-arginine deiminase-4-dependent immunothrombosis.

OBJECTIVE: Bleeding ulcers and erosions are hallmarks of active ulcerative colitis (UC). However, the mechanisms controlling bleeding and mucosal haemostasis remain elusive. DESIGN: We used high-resolution endoscopy and colon tissue samples of active UC (n = 36) as well as experimental models of physical and chemical mucosal damage in mice deficient for peptidyl-arginine deiminase-4 (PAD4), gnotobiotic mice and controls. We employed endoscopy, histochemistry, live-cell microscopy and flow cytometry to study eroded mucosal surfaces during mucosal haemostasis. RESULTS: Erosions and ulcerations in UC were covered by fresh blood, haematin or fibrin visible by endoscopy. Fibrin layers rather than fresh blood or haematin on erosions were inversely correlated with rectal bleeding in UC. Fibrin layers contained ample amounts of neutrophils coaggregated with neutrophil extracellular traps (NETs) with detectable activity of PAD. Transcriptome analyses showed significantly elevated PAD4 expression in active UC. In experimentally inflicted wounds, we found that neutrophils underwent NET formation in a PAD4-dependent manner hours after formation of primary blood clots, and remodelled clots to immunothrombi containing citrullinated histones, even in the absence of microbiota. PAD4-deficient mice experienced an exacerbated course of dextrane sodium sulfate-induced colitis with markedly increased rectal bleeding (96 % vs 10 %) as compared with controls. PAD4-deficient mice failed to remodel blood clots on mucosal wounds eliciting impaired healing. Thus, NET-associated immunothrombi are protective in acute colitis, while insufficient immunothrombosis is associated with rectal bleeding. CONCLUSION: Our findings uncover that neutrophils induce secondary immunothrombosis by PAD4-dependent mechanisms. Insufficient immunothrombosis may favour rectal bleeding in UC.

High-resolution mapping reveals that microniches in the gastric glands control Helicobacter pylori colonization of the stomach.

Lifelong infection of the gastric mucosa by Helicobacter pylori can lead to peptic ulcers and gastric cancer. However, how the bacteria maintain chronic colonization in the face of constant mucus and epithelial cell turnover in the stomach is unclear. Here, we present a new model of how H. pylori establish and persist in stomach, which involves the colonization of a specialized microenvironment, or microniche, deep in the gastric glands. Using quantitative three-dimensional (3D) confocal microscopy and passive CLARITY technique (PACT), which renders tissues optically transparent, we analyzed intact stomachs from mice infected with a mixture of isogenic, fluorescent H. pylori strains with unprecedented spatial resolution. We discovered that a small number of bacterial founders initially establish colonies deep in the gastric glands and then expand to colonize adjacent glands, forming clonal population islands that persist over time. Gland-associated populations do not intermix with free-swimming bacteria in the surface mucus, and they compete for space and prevent newcomers from establishing in the stomach. Furthermore, bacterial mutants deficient in gland colonization are outcompeted by wild-type (WT) bacteria. Finally, we found that host factors such as the age at infection and T-cell responses control bacterial density within the glands. Collectively, our results demonstrate that microniches in the gastric glands house a persistent H. pylori reservoir, which we propose replenishes the more transient bacterial populations in the superficial mucosa.

Short-Wave Infrared Emitting Nanocomposites for Fluorescence-Guided Surgery.

Fluorescence-guided surgery (FGS) is an emerging technique for tissue visualization during surgical procedures. Structures of interest are labeled with exogenous probes whose fluorescent emissions are acquired and viewed in real-time with optical imaging systems. This study investigated rare-earth-doped albumin-encapsulated nanocomposites (REANCs) as short-wave infrared emitting contrast agents for FGS. Experiments were conducted using an animal model of 4T1 breast cancer. The signal-to-background ratio (SBR) obtained with REANCs was compared to values obtained using indocyanine green (ICG), a near-infrared dye used in clinical practice. Prior to resection, the SBR for tumors following intratumoral administration of REANCs was significantly higher than for tumors injected with ICG. Following FGS, evaluation of fluorescence intensity levels in excised tumors and at the surgical bed demonstrated higher contrast between tissues at these sites with REANC contrast than ICG. REANCs also demonstrated excellent photostability over 2 hours of continuous illumination, as well as the ability to perform FGS under ambient lighting, establishing these nanocomposites as a promising contrast agent for FGS applications.

Identification of Pathogenicity Island Genes Associated with Loss of Type IV Secretion Function during Murine Infection with Helicobacter pylori.

Chronic Helicobacter pylori colonization in animal models often leads to downregulation of the type IV secretion system (T4SS), typically by recombination in cagY, which is an essential T4SS gene. However, 17 other cag pathogenicity island (cagPAI) genes, as well as some non-cagPAI genes, are also essential for T4SS function. To get a more complete picture of how H. pylori regulates the T4SS during animal colonization, we examined cagY in 534 mouse-passaged isolates that lost T4SS function, defined as a normalized interleukin-8 (IL-8) value of <0.3 relative to the input H. pylori strain PMSS1. In order to analyze the genetic changes in the strains with unchanged cagY, we sequenced the entire pathogenicity island of 60 such isolates using single-molecule, real-time (SMRT) sequencing technology (PacBio, Menlo Park, CA), and we compared the results to the PMSS1 wild type (WT). Of the 534 strains, 271 (51%) showed evidence of recombination in cagY, but we also found indels or nonsynonymous changes in 13 other essential cagPAI genes implicated in H. pylori T4SS function, most commonly cag5, cag10, and cagA While cagY recombination is the most common mechanism by which H. pylori downregulates T4SS function during murine infection, loss of function is also associated with changes in other essential cagPAI genes.

How Introducing a Registry With Automated Alerts for Carbapenem-resistant Enterobacteriaceae (CRE) May Help Control CRE Spread in a Region.

BACKGROUND: Regions are considering the use of electronic registries to track patients who carry antibiotic-resistant bacteria, including carbapenem-resistant Enterobacteriaceae (CRE). Implementing such a registry can be challenging and requires time, effort, and resources; therefore, there is a need to better understand the potential impact. METHODS: We developed an agent-based model of all inpatient healthcare facilities (90 acute care hospitals, 9 long-term acute care hospitals, 351 skilled nursing facilities, and 12 ventilator-capable skilled nursing facilities) in the Chicago metropolitan area, surrounding communities, and patient flow using our Regional Healthcare Ecosystem Analyst software platform. Scenarios explored the impact of a registry that tracked patients carrying CRE to help guide infection prevention and control. RESULTS: When all Illinois facilities participated (n = 402), the registry reduced the number of new carriers by 11.7% and CRE prevalence by 7.6% over a 3-year period. When 75% of the largest Illinois facilities participated (n = 304), registry use resulted in a 11.6% relative reduction in new carriers (16.9% and 1.2% in participating and nonparticipating facilities, respectively) and 5.0% relative reduction in prevalence. When 50% participated (n = 201), there were 10.7% and 5.6% relative reductions in incident carriers and prevalence, respectively. When 25% participated (n = 101), there was a 9.1% relative reduction in incident carriers (20.4% and 1.6% in participating and nonparticipating facilities, respectively) and 2.8% relative reduction in prevalence. CONCLUSIONS: Implementing an extensively drug-resistant organism registry reduced CRE spread, even when only 25% of the largest Illinois facilities participated due to patient sharing. Nonparticipating facilities garnered benefits, with reductions in new carriers.

Association of carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis with the HLA-B75 serotype or HLA-B*15:21 allele in Filipino patients.

A case-control study was conducted to investigate the association of HLA-A alleles, HLA-B alleles including HLA-B*15:02 and HLA-B75 serotype with carbamazepine-induced SJS/TEN in Filipino patients. A retrospective review of medical records was performed. Pertinent clinical data were collected. Eight (8) carbamazepine-induced SJS/TEN cases and 32 tolerant controls were recruited. Genomic DNA was extracted from the saliva samples and genotyping was performed by employing allele-specific polymerase chain reaction. Data were analyzed using the Fisher's exact test, Mann-Whitney U test, univariate logistic regression, and multivariate logistic regression. Single allele association analysis was done. The strength of association was expressed as odds ratio with 95% confidence interval. Positive predictive value, negative predictive value, sensitivity, and specificity were computed. Of all the alleles tested, the HLA-B75 serotype (p = 0.007, OR = 23.25, 95% CI = 2.33-232.21) and HLA-B*15:21 (p = 0.026, OR = 7.53, 95% CI = 1.27-44.79) were significantly associated with carbamazepine-induced SJS/TEN. The HLA-B75 serotype or HLA-B*15:21 allele may be used as a genetic risk assessment prior to prescription for prevention of carbamazepine-induced SJS/TEN in Filipino patients.

Impact of Helicobacter pylori Virulence Factors on the Host Immune Response and Gastric Pathology.

Helicobacter pylori chronically infects nearly half the world's population, yet most of those infected remain asymptomatic throughout their lifetime. The outcome of infection-peptic ulcer disease or gastric cancer versus asymptomatic colonization-is a product of host genetics, environmental influences, and differences in bacterial virulence factors. Here, we review the current understanding of the cag pathogenicity island (cagPAI), the vacuolating cytotoxin (VacA), and a large family of outer membrane proteins (OMPs), which are among the best understood H. pylori virulence determinants that contribute to disease. Each of these virulence factors is characterized by allelic and phenotypic diversity that is apparent within and across individuals, as well as over time, and modulates inflammation. From the bacterial perspective, inflammation is probably a necessary evil because it promotes nutrient acquisition, but at the cost of reduction in bacterial load and therefore decreases the chance of transmission to a new host. The general picture that emerges is one of a chronic bacterial infection that is dependent on both inducing and carefully regulating the host inflammatory response. A better understanding of these regulatory mechanisms may have implications for the control of chronic inflammatory diseases that are increasingly common causes of human morbidity and mortality.

Therapeutic modulation of the bile acid pool by Cyp8b1 knockdown protects against nonalcoholic fatty liver disease in mice.

Bile acids (BAs) are surfactant molecules that regulate the intestinal absorption of lipids. Thus, the modulation of BAs represents a potential therapy for nonalcoholic fatty liver disease (NAFLD), which is characterized by hepatic accumulation of fat and is a major cause of liver disease worldwide. Cyp8b1 is a critical modulator of the hydrophobicity index of the BA pool. As a therapeutic proof of concept, we aimed to determine the impact of Cyp8b1 inhibition in vivo on BA pool composition and as protection against NAFLD. Inhibition of Cyp8b1 expression in mice led to a remodeling of the BA pool, which altered its signaling properties and decreased intestinal fat absorption. In a model of cholesterol-induced NAFLD, Cyp8b1 knockdown significantly decreased steatosis and hepatic lipid content, which has been associated with an increase in fecal lipid and BA excretion. Moreover, inhibition of Cyp8b1 not only decreased hepatic lipid accumulation, but also resulted in the clearance of previously accumulated hepatic cholesterol, which led to a regression in hepatic steatosis. Taken together, our data demonstrate that Cyp8b1 inhibition is a viable therapeutic target of crucial interest for metabolic diseases, such as NAFLD.-Chevre, R., Trigueros-Motos, L., Castaño, D., Chua, T., Corlianò, M., Patankar, J. V., Sng, L., Sim, L., Juin, T. L., Carissimo, G., Ng, L. F. P., Yi, C. N. J., Eliathamby, C. C., Groen, A. K., Hayden, M. R., Singaraja, R. R. Therapeutic modulation of the bile acid pool by Cyp8b1 knockdown protects against nonalcoholic fatty liver disease in mice.

Genetic ablation of Cyp8b1 preserves host metabolic function by repressing steatohepatitis and altering gut microbiota composition.

Both type 2 diabetes (T2D) and nonalcoholic steatohepatitis (NASH) are associated with reduced hepatic mitochondrial respiratory capacity. Cholic acid (CA) is the predominant 12α-hydroxylated bile acid that regulates hepatic lipid metabolism, and its circulating levels are negatively correlated with insulin resistance. Abolishing CA synthesis via the genetic disruption of the enzyme sterol 12α-hydroxylase ( Cyp8b1-/-) leads in resistance to diabetes and hepatic steatosis. Here, we show that long-term stimulation of hepatic lipogenesis leads to a severe impairment in overall metabolic and respiratory function in control mice ( Cyp8b1+/+) but strikingly not in Cyp8b1-/- mice. Cyp8b1-/- mice are protected from such metabolic impairments associated with T2D and NASH by inhibiting hepatic de novo lipogenic gene and protein expression and altering gut microbiota composition. The protective phenotype is compromised when NASH induction is independent of impairment in de novo lipogenesis (DNL). Consequently, Cyp8b1-/- mice also show a reduction in hepatic inflammation and fibrosis along with a shift in antimicrobial dynamics in the small intestine. Our data show that the altered bile acid composition of Cyp8b1-/- mice preserves metabolic and respiratory function by repressing hepatic DNL and driving favorable changes in gut antimicrobial responses.

Erythropoietin Does Not Alter Serum Profiles of Neuronal and Axonal Biomarkers After Traumatic Brain Injury: Findings From the Australian EPO-TBI Clinical Trial.

OBJECTIVE: To determine profiles of serum ubiquitin carboxy-terminal hydrolase L1 and phosphorylated neurofilament heavy-chain, examine whether erythropoietin administration reduce their concentrations, and whether biomarkers discriminate between erythropoietin and placebo treatment groups. DESIGN: Single-center, prospective observational study. SETTING: A sub-study of the erythropoietin-traumatic brain injury clinical trial, conducted at the Alfred Hospital, Melbourne, Australia. PATIENTS: Forty-four patients with moderate-to-severe traumatic brain injury. INTERVENTIONS: Epoetin alfa 40,000 IU or 1 mL sodium chloride 0.9 as subcutaneous injection within 24 hours of traumatic brain injury. MEASUREMENTS AND MAIN RESULTS: Ubiquitin carboxy-terminal hydrolase L1, phosphorylated neurofilament heavy-chain, and erythropoietin concentrations were measured in serum by enzyme-linked immunosorbent assay from D0 (within 24 hr of injury, prior to erythropoietin/vehicle administration) to D5. Biomarker concentrations were compared between injury severities, diffuse versus focal traumatic brain injury and erythropoietin or placebo treatment groups. Ubiquitin carboxy-terminal hydrolase L1 peaked at 146.0 ng/mL on D0, significantly decreased to 84.30 ng/mL on D1, and declined thereafter. Phosphorylated neurofilament heavy-chain levels were lowest at D0 and peaked on D5 at 157.9 ng/mL. D0 ubiquitin carboxy-terminal hydrolase L1 concentrations were higher in diffuse traumatic brain injury. Peak phosphorylated neurofilament heavy-chain levels on D3 and D4 correlated with Glasgow Outcome Score-Extended, predicting poor outcome. Erythropoietin did not reduce concentrations of ubiquitin carboxy-terminal hydrolase L1 or phosphorylated neurofilament heavy-chain. CONCLUSIONS: Serum ubiquitin carboxy-terminal hydrolase L1 and phosphorylated neurofilament heavy-chain increase after traumatic brain injury reflecting early neuronal and progressive axonal injury. Consistent with lack of improved outcome in traumatic brain injury patients treated with erythropoietin, biomarker concentrations and profiles were not affected by erythropoietin. Pharmacokinetics of erythropoietin suggest that the dose given was possibly too low to exert neuroprotection.

Effects of age and sex ratios on offspring recruitment rates in translocated black rhinoceros.

Success of animal translocations depends on improving postrelease demographic rates toward establishment and subsequent growth of released populations. Short-term metrics for evaluating translocation success and its drivers, like postrelease survival and fecundity, are unlikely to represent longer-term outcomes. We used information theory to investigate 25 years of data on black rhinoceros (Diceros bicornis) translocations. We used the offspring recruitment rate (ORR) of translocated females-a metric integrating survival, fecundity, and offspring recruitment at sexual maturity-to detect determinants of success. Our unambiguously best model (AICω = 0.986) predicted that ORR increases with female age at release as a function of lower postrelease adult rhinoceros sex ratio (males:females). Delay of first postrelease reproduction and failure of some females to recruit any calves to sexual maturity most influenced the pattern of ORRs, and the leading causes of recruitment failure were postrelease female death (23% of all females) and failure to calve (24% of surviving females). We recommend translocating older females (≥6 years old) because they do not exhibit the reproductive delay and low ORRs of juveniles (<4 years old) or the higher rates of recruitment failure of juveniles and young adults (4-5.9 years old). Where translocation of juveniles is necessary, they should be released into female-biased populations, where they have higher ORRs. Our study offers the unique advantage of a long-term analysis across a large number of replicate populations-a science-by-management experiment as a proxy for a manipulative experiment, and a rare opportunity, particularly for a large, critically endangered taxon such as the black rhinoceros. Our findings differ from previous recommendations, reinforce the importance of long-term data sets and comprehensive metrics of translocation success, and suggest attention be shifted from ecological to social constraints on population growth and species recovery, particularly when translocating species with polygynous breeding systems.

Dynamic Expression of the BabA Adhesin and Its BabB Paralog during Helicobacter pylori Infection in Rhesus Macaques.

Most Helicobacter pylori strains express the BabA adhesin, which binds to ABO/Leb blood group antigens on gastric mucin and epithelial cells and is found more commonly in strains that cause peptic ulcers or gastric cancer, rather than asymptomatic infection. We and others have previously reported that in mice, gerbils, and rhesus macaques, expression of babA is lost, either by phase variation or by gene conversion, in which the babB paralog recombines into the babA locus. The functional significance of loss of babA expression is unknown. Here we report that in rhesus monkeys, there is independent selective pressure for loss of babA and for overexpression of BabB, which confers a fitness advantage. Surprisingly, loss of babA by phase variation or gene conversion is not dependent on the capacity of BabA protein to bind Leb, which suggests that it may have other, unrecognized functions. These findings have implications for the role of outer membrane protein diversity in persistent H. pylori infection.

Novel role of a triglyceride-synthesizing enzyme: DGAT1 at the crossroad between triglyceride and cholesterol metabolism.

Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in triacylglycerol (TG) biosynthesis. Here we show that genetic deficiency and pharmacological inhibition of DGAT1 in mice alters cholesterol metabolism. Cholesterol absorption, as assessed by acute cholesterol uptake, was significantly decreased in the small intestine and liver upon DGAT1 deficiency/inhibition. Ablation of DGAT1 in the intestine (I-DGAT1(-/-)) alone is sufficient to cause these effects. Consequences of I-DGAT1 deficiency phenocopy findings in whole-body DGAT1(-/-) and DGAT1 inhibitor-treated mice. We show that deficiency/inhibition of DGAT1 affects cholesterol metabolism via reduced chylomicron size and increased trans-intestinal cholesterol excretion. These effects are independent of cholesterol uptake at the apical surface of enterocytes but mediated through altered dietary fatty acid metabolism. Our findings provide insight into a novel role of DGAT1 and identify a pathway by which intestinal DGAT1 deficiency affects whole-body cholesterol homeostasis in mice. Targeting intestinal DGAT1 may represent a novel approach for treating hypercholesterolemia.

Does Choice of Influenza Vaccine Type Change Disease Burden and Cost-Effectiveness in the United States? An Agent-Based Modeling Study.

Offering a choice of influenza vaccine type may increase vaccine coverage and reduce disease burden, but it is more costly. This study calculated the public health impact and cost-effectiveness of 4 strategies: no choice, pediatric choice, adult choice, or choice for both age groups. Using agent-based modeling, individuals were simulated as they interacted with others, and influenza was tracked as it spread through a population in Washington, DC. Influenza vaccination coverage derived from data from the Centers for Disease Control and Prevention was increased by 6.5% (range, 3.25%-11.25%), reflecting changes due to vaccine choice. With moderate influenza infectivity, the number of cases averaged 1,117,285 for no choice, 1,083,126 for pediatric choice, 1,009,026 for adult choice, and 975,818 for choice for both age groups. Averted cases increased with increased coverage and were highest for the choice-for-both-age-groups strategy; adult choice also reduced cases in children. In cost-effectiveness analysis, choice for both age groups was dominant when choice increased vaccine coverage by ≥3.25%. Offering a choice of influenza vaccines, with reasonable resultant increases in coverage, decreased influenza cases by >100,000 with a favorable cost-effectiveness profile. Clinical trials testing the predictions made based on these simulation results and deliberation of policies and procedures to facilitate choice should be considered.

CagY Is an Immune-Sensitive Regulator of the Helicobacter pylori Type IV Secretion System.

BACKGROUND & AIMS: Peptic ulcer disease and gastric cancer are caused most often by Helicobacter pylori strains that harbor the cag pathogenicity island, which encodes a type IV secretion system (T4SS) that injects the CagA oncoprotein into host cells. cagY is an essential gene in the T4SS and has an unusual DNA repeat structure that predicts in-frame insertions and deletions. These cagY recombination events typically lead to a reduction in T4SS function in mouse and primate models. We examined the role of the immune response in cagY-dependent modulation of T4SS function. METHODS: H pylori T4SS function was assessed by measuring CagA translocation and the capacity to induce interleukin (IL)8 in gastric epithelial cells. cagY recombination was determined by changes in polymerase chain reaction restriction fragment-length polymorphisms. T4SS function and cagY in H pylori from C57BL/6 mice were compared with strains recovered from Rag1-/- mice, T- and B-cell-deficient mice, mice with deletion of the interferon gamma receptor (IFNGR) or IL10, and Rag1-/- mice that received adoptive transfer of control or Ifng-/- CD4+ T cells. To assess relevance to human beings, T4SS function and cagY recombination were assessed in strains obtained sequentially from a patient after 7.4 years of infection. RESULTS: H pylori infection of T-cell-deficient and Ifngr1-/- mice, and transfer of CD4+ T cells to Rag1-/- mice, showed that cagY-mediated loss of T4SS function requires a T-helper 1-mediated immune response. Loss of T4SS function and cagY recombination were more pronounced in Il10-/- mice, and in control mice infected with H pylori that expressed a more inflammatory form of cagY. Complementation analysis of H pylori strains isolated from a patient over time showed changes in T4SS function that were dependent on recombination in cagY. CONCLUSIONS: Analysis of H pylori strains from mice and from a chronically infected patient showed that CagY functions as an immune-sensitive regulator of T4SS function. We propose that this is a bacterial adaptation to maximize persistent infection and transmission to a new host under conditions of a robust inflammatory response.