Immunomodulatory Functions of BTLA and HVEM Govern Induction of Extrathymic Regulatory T Cells and Tolerance by Dendritic Cells.

Dendritic cells (DCs) initiate immunity and also antigen-specific tolerance mediated by extrathymic regulatory T (Treg) cells, yet it remains unclear how DCs regulate induction of such tolerance. Here, we report that efficient induction of Treg cells was instructed by BTLA+DEC205+CD8+CD11c+ DCs and the immunomodulatory functions of BTLA. In contrast, T cell activation in steady state by total CD11c+ DCs that include a majority of DCs that do not express BTLA did not induce Treg cells and had no lasting impact on subsequent immune responses. Engagement of HVEM, a receptor of BTLA, promoted Foxp3 expression in T cells through upregulation of CD5. In contrast, T cells activated in the absence of BTLA and HVEM-mediated functions remained CD5lo and therefore failed to resist the inhibition of Foxp3 expression in response to effector cell-differentiating cytokines. Thus, DCs require BTLA and CD5-dependent mechanisms to actively adjust tolerizing T cell responses under steady-state conditions.

CD5 instructs extrathymic regulatory T cell development in response to self and tolerizing antigens.

Self-reactive T cells can escape thymic deletion and therefore some of these potentially autoaggressive T cells need to convert into regulatory T (Treg) cells to help control responses against self. However, it remains unknown how peripheral self-reactive T cells are specifically instructed to become Treg cells. We report that CD5, whose expression is upregulated in T cells by self and tolerizing antigens in the thymus and periphery, governed extrathymic Treg cell development. CD5 modified effector cell-differentiating signals that inhibit Treg cell induction. Treg cell conversion of Cd5(-/-) and CD5(lo) T cells was inhibited by even small amounts of interleukin-4 (IL-4), IL-6, and interferon-γ (IFN-γ) produced by bystander lymphocytes, while CD5(hi) T cells resisted this inhibition of Treg cell induction. Our findings further revealed that CD5 promoted Treg cell induction by blocking mechanistic target of rapamycin (mTOR) activation. Therefore CD5 instructs extrathymic Treg cell development in response to self and tolerizing antigens.

Changes in Prevalence of Health Care-Associated Infections in U.S. Hospitals.

BACKGROUND: A point-prevalence survey that was conducted in the United States in 2011 showed that 4% of hospitalized patients had a health care-associated infection. We repeated the survey in 2015 to assess changes in the prevalence of health care-associated infections during a period of national attention to the prevention of such infections. METHODS: At Emerging Infections Program sites in 10 states, we recruited up to 25 hospitals in each site area, prioritizing hospitals that had participated in the 2011 survey. Each hospital selected 1 day on which a random sample of patients was identified for assessment. Trained staff reviewed medical records using the 2011 definitions of health care-associated infections. We compared the percentages of patients with health care-associated infections and performed multivariable log-binomial regression modeling to evaluate the association of survey year with the risk of health care-associated infections. RESULTS: In 2015, a total of 12,299 patients in 199 hospitals were surveyed, as compared with 11,282 patients in 183 hospitals in 2011. Fewer patients had health care-associated infections in 2015 (394 patients [3.2%; 95% confidence interval {CI}, 2.9 to 3.5]) than in 2011 (452 [4.0%; 95% CI, 3.7 to 4.4]) (P<0.001), largely owing to reductions in the prevalence of surgical-site and urinary tract infections. Pneumonia, gastrointestinal infections (most of which were due to Clostridium difficile [now Clostridioides difficile]), and surgical-site infections were the most common health care-associated infections. Patients' risk of having a health care-associated infection was 16% lower in 2015 than in 2011 (risk ratio, 0.84; 95% CI, 0.74 to 0.95; P=0.005), after adjustment for age, presence of devices, days from admission to survey, and status of being in a large hospital. CONCLUSIONS: The prevalence of health care-associated infections was lower in 2015 than in 2011. To continue to make progress in the prevention of such infections, prevention strategies against C. difficile infection and pneumonia should be augmented. (Funded by the Centers for Disease Control and Prevention.).

Peripherally Induced Tolerance Depends on Peripheral Regulatory T Cells That Require Hopx To Inhibit Intrinsic IL-2 Expression.

Dendritic cells (DCs) can induce peripheral immune tolerance that prevents autoimmune responses. Ag presentation by peripheral DCs under steady-state conditions leads to a conversion of some peripheral CD4(+) T cells into regulatory T cells (Tregs) that require homeodomain-only protein (Hopx) to mediate T cell unresponsiveness. However, the roles of these peripheral Tregs (pTregs) in averting autoimmune responses, as well as immunological mechanisms of Hopx, remain unknown. We report that Hopx(+) pTregs converted by DCs from Hopx(-) T cells are indispensible to sustain tolerance that prevents autoimmune responses directed at self-Ags during experimental acute encephalomyelitis. Our studies further reveal that Hopx inhibits intrinsic IL-2 expression in pTregs after antigenic rechallenge. In the absence of Hopx, increased levels of IL-2 lead to death and decreased numbers of pTregs. Therefore, formation of Hopx(+) pTregs represents a crucial pathway of sustained tolerance induced by peripheral DCs, and the maintenance of such pTregs and tolerance requires functions of Hopx to block intrinsic IL-2 production in pTregs.

Incidence and Characteristics of Ventilator-Associated Events Reported to the National Healthcare Safety Network in 2014.

OBJECTIVE: Ventilator-associated event surveillance was introduced in the National Healthcare Safety Network in 2013, replacing surveillance for ventilator-associated pneumonia in adult inpatient locations. We determined incidence rates and characteristics of ventilator-associated events reported to the National Healthcare Safety Network. DESIGN, SETTING, AND PATIENTS: We analyzed data reported from U.S. healthcare facilities for ventilator-associated events that occurred in 2014, the first year during which ventilator-associated event surveillance definitions were stable. We used negative binomial regression modeling to identify healthcare facility and inpatient location characteristics associated with ventilator-associated events. We calculated ventilator-associated event incidence rates, rate distributions, and ventilator utilization ratios in critical care and noncritical care locations and described event characteristics. MEASUREMENTS AND MAIN RESULTS: A total of 1,824 healthcare facilities reported 32,772 location months of ventilator-associated event surveillance data to the National Healthcare Safety Network in 2014. Critical care unit pooled mean ventilator-associated event incidence rates ranged from 2.00 to 11.79 per 1,000 ventilator days, whereas noncritical care unit rates ranged from 0 to 14.86 per 1,000 ventilator days. The pooled mean proportion of ventilator-associated events defined as infection-related varied from 15.38% to 47.62% in critical care units. Pooled mean ventilator utilization ratios in critical care units ranged from 0.24 to 0.47. CONCLUSIONS: We found substantial variability in ventilator-associated event incidence, proportions of ventilator-associated events characterized as infection-related, and ventilator utilization within and among location types. More work is needed to understand the preventable fraction of ventilator-associated events and identify patient care strategies that reduce ventilator-associated events.

Pathogens attributed to central-line-associated bloodstream infections in US acute-care hospitals during the first year of the coronavirus disease 2019 (COVID-19) pandemic.

To assess potential changes in the pathogens attributed to central-line-associated bloodstream infections between 2019 and 2020, hospital data from the National Healthcare Safety Network were analyzed. Compared to 2019, increases in the proportions of pathogens identified as Enterococcus faecalis and coagulase-negative staphylococci were observed during 2020.

Evaluation of potential gastrointestinal biomarkers in a PAK4 inhibitor-treated preclinical toxicity model to address unmonitorable gastrointestinal toxicity.

Although gastrointestinal (GI) toxicity is a significant dose-limiting safety concern noted in multiple therapeutic areas, there are no GI biomarkers that can accurately track, precede, or reliably correlate with histologic evidence of injury. While significant efforts have been made within the pharmaceutical industry, academia, and consortia to address the biomarker gaps in other target organs such as liver, kidney, and muscle (cardiac and skeletal), there have been no concerted efforts in the area of GI biomarkers. Using PAK4 inhibitor as a preclinical rat model of gastric toxicity, selected candidate biomarkers from literature were evaluated to test their usefulness as gastric injury biomarkers in this study. Biomarkers selected in this study include plasma diamino oxidase and citrulline, fecal calprotectin, bile acids, and miRNA. Based on the results, L-citrulline and miR-194 results appear to correlate well with histopathology findings. Although these biomarkers will need additional assay validation and qualification to test if they truly predict the injury prior to histopathology, the results provide promise for further testing using additional GI toxicants. In addition, this article highlights important gaps in GI biomarkers and provides substrate and rationale for additional investments either for further testing of already available biomarkers or to pursue extensive biomarker discovery approaches.

Changes in the number of intensive care unit beds in US hospitals during the early months of the coronavirus disease 2019 (COVID-19) pandemic.

Using data from the National Healthcare Safety Network (NHSN), we assessed changes to intensive care unit (ICU) bed capacity during the early months of the COVID-19 pandemic. Changes in capacity varied by hospital type and size. ICU beds increased by 36%, highlighting the pressure placed on hospitals during the pandemic.

Hospital capacities and shortages of healthcare resources among US hospitals during the coronavirus disease 2019 (COVID-19) pandemic, National Healthcare Safety Network (NHSN), March 27-July 14, 2020.

During March 27-July 14, 2020, the Centers for Disease Control and Prevention's National Healthcare Safety Network extended its surveillance to hospital capacities responding to COVID-19 pandemic. The data showed wide variations across hospitals in case burden, bed occupancies, ventilator usage, and healthcare personnel and supply status. These data were used to inform emergency responses.

Impact of coronavirus disease 2019 (COVID-19) on US Hospitals and Patients, April-July 2020.

OBJECTIVE: The rapid spread of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) throughout key regions of the United States in early 2020 placed a premium on timely, national surveillance of hospital patient censuses. To meet that need, the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN), the nation's largest hospital surveillance system, launched a module for collecting hospital coronavirus disease 2019 (COVID-19) data. We present time-series estimates of the critical hospital capacity indicators from April 1 to July 14, 2020. DESIGN: From March 27 to July 14, 2020, the NHSN collected daily data on hospital bed occupancy, number of hospitalized patients with COVID-19, and the availability and/or use of mechanical ventilators. Time series were constructed using multiple imputation and survey weighting to allow near-real-time daily national and state estimates to be computed. RESULTS: During the pandemic's April peak in the United States, among an estimated 431,000 total inpatients, 84,000 (19%) had COVID-19. Although the number of inpatients with COVID-19 decreased from April to July, the proportion of occupied inpatient beds increased steadily. COVID-19 hospitalizations increased from mid-June in the South and Southwest regions after stay-at-home restrictions were eased. The proportion of inpatients with COVID-19 on ventilators decreased from April to July. CONCLUSIONS: The NHSN hospital capacity estimates served as important, near-real-time indicators of the pandemic's magnitude, spread, and impact, providing quantitative guidance for the public health response. Use of the estimates detected the rise of hospitalizations in specific geographic regions in June after they declined from a peak in April. Patient outcomes appeared to improve from early April to mid-July.

Landscape of Hopx expression in cells of the immune system.

Homeodomain only protein (Hopx) is a regulator of cell differentiation and function, and it has also emerged as a crucial marker of specific developmental and differentiation potentials. Hopx expression and functions have been identified in some stem cells, tumors, and in certain immune cells. However, expression of Hopx in immune cells remains insufficiently characterized. Here we report a comprehensive pattern of Hopx expression in multiple types of immune cells under steady state conditions. By utilizing single-cell RNA sequencing (scRNA-seq) and flow cytometric analysis, we characterize a constitutive expression of Hopx in specific subsets of CD4+ and CD8+ T cells and B cells, as well as natural killer (NK), NKT, and myeloid cells. In contrast, Hopx expression is not present in conventional dendritic cells and eosinophils. The utility of identifying expression of Hopx in immune cells may prove vital in delineating specific roles of Hopx under multiple immune conditions.

Healthcare-associated infections studies project: An American Journal of Infection Control and National Healthcare Safety Network data quality collaboration.

This case study is part of a series centered on the Centers for Disease Control and Prevention/National Healthcare Safety Network (NHSN) healthcare-associated infection (HAI) surveillance definitions. This specific case study focuses on the application of the Pneumonia (PNEU), Ventilator-associated event (VAE), and Bloodstream infections (BSI) surveillance definitions to a patient with COVID-19. The intent of the case study series is to foster standardized application of the NHSN HAI surveillance definitions among Infection Preventionists (IPs) and encourage accurate determination of HAI events.

Acute lymphoid and gastrointestinal toxicity induced by selective p38alpha map kinase and map kinase-activated protein kinase-2 (MK2) inhibitors in the dog.

Exposure to moderately selective p38alpha mitogen-activated protein kinase (MAPK) inhibitors in the Beagle dog results in an acute toxicity consisting of mild clinical signs (decreased activity, diarrhea, and fever), lymphoid necrosis and depletion in the gut-associated lymphoid tissue (GALT), mesenteric lymph nodes and spleen, and linear colonic and cecal mucosal hemorrhages. Lymphocyte apoptosis and necrosis in the GALT is the earliest and most prominent histopathologic change observed, followed temporally by neutrophilic infiltration and acute inflammation of the lymph nodes and spleen and multifocal mucosal epithelial necrosis and linear hemorrhages in the colon and cecum. These effects are not observed in the mouse, rat, or cynomolgus monkey. To further characterize the acute toxicity in the dog, a series of in vivo, in vitro, and immunohistochemical studies were conducted to determine the relationship between the lymphoid and gastrointestinal (GI) toxicity and p38 MAPK inhibition. Results of these studies demonstrate a direct correlation between p38alpha MAPK inhibition and the acute lymphoid and gastrointestinal toxicity in the dog. Similar effects were observed following exposure to inhibitors of MAPK-activated protein kinase-2 (MK2), further implicating the role of p38alpha MAPK signaling pathway inhibition in these effects. Based on these findings, the authors conclude that p38alpha MAPK inhibition results in acute lymphoid and GI toxicity in the dog and is unique among the species evaluated in these studies.

Health care-associated infections studies project: an American Journal of Infection Control and National Healthcare Safety Network data quality collaboration.

This case study is part of a series centered on the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN) health care-associated infection (HAI) surveillance definitions. The intent of the case study series is to foster standardized application of the NHSN HAI surveillance definitions among infection preventionists and to promote accurate determination of HAI events. These cases reflect some of the complex patient scenarios that infection preventionists have encountered in their daily surveillance of HAIs using NHSN definitions. Objectives have been previously published.1.

A Two-Step Process of Effector Programming Governs CD4+ T Cell Fate Determination Induced by Antigenic Activation in the Steady State.

Various processes induce and maintain immune tolerance, but effector T cells still arise under minimal perturbations of homeostasis through unclear mechanisms. We report that, contrary to the model postulating primarily tolerogenic mechanisms initiated under homeostatic conditions, effector programming is an integral part of T cell fate determination induced by antigenic activation in the steady state. This effector programming depends on a two-step process starting with induction of effector precursors that express Hopx and are imprinted with multiple instructions for their subsequent terminal effector differentiation. Such molecular circuits advancing specific terminal effector differentiation upon re-stimulation include programmed expression of interferon-γ, whose production then promotes expression of T-bet in the precursors. We further show that effector programming coincides with regulatory conversion among T cells sharing the same antigen specificity. However, conventional type 2 dendritic cells (cDC2) and T cell functions of mammalian target of rapamycin complex 1 (mTORC1) increase effector precursor induction while decreasing the proportion of T cells that can become peripheral Foxp3+ regulatory T (pTreg) cells.

Health care-associated infections studies project: An American Journal of Infection Control and National Healthcare Safety Network data quality collaboration case study: Bloodstream infection-patient injection into vascular access 2018.

This case study is part of a series centered on the Centers for Disease Control and Prevention/National Healthcare Safety Network (NHSN) health care-associated infection surveillance definitions. These cases reflect some of the complex patient scenarios infection preventionists have encountered in their daily surveillance of health care-associated infections using NHSN definitions and protocols. Teaching points for this case study are.

Health care-associated infections studies project: An American Journal of Infection Control and National Healthcare Safety Network data quality collaboration.

This case study is part of a series centered on the Centers for Disease Control and Prevention's National Healthcare Safety Network's (NHSN) health care-associated infection (HAI) surveillance definitions. The intent of the case study series is to foster standardized application of the NHSN's HAI surveillance definitions among infection preventionists and accurate determination of HAI events. This specific case study focuses on the definitions found within the surgical site infection (SSI) protocol. It aims to reflect the real life and complex patient scenario surrounding a bloodstream infection that is secondary to an SSI and the application of the Present at the Time of Surgery event detail. An online survey link is provided where participants may confidentially answer questions related to the case study and receive immediate feedback in the form of correct answers and explanations and rationales. Details of the case study, answers, and explanations have been reviewed and approved by NHSN staff. We hope that participants take advantage of this educational offering and thereby gain a greater understanding of the NHSN's HAI surveillance definitions.

Health care-associated infections studies project: An American Journal of Infection Control and National Healthcare Safety Network data quality collaboration.

This case study is part of a series centered on the Centers for Disease Control and Prevention/National Healthcare Safety Network (NHSN) health care-associated infection (HAI) surveillance definitions. This specific case study focuses on the definitions and protocols used to make HAI infection determinations, such as the infection window period and secondary bloodstream infection attribution period. The case reflects the real-life and complex patient scenarios that infection preventionists (IPs) face when identifying and reporting HAIs to NHSN. The intent of the case study series is to foster standardized application of the NHSN HAI surveillance definitions among IPs and encourage accurate determination of HAI events. An online survey link is provided where participants may confidentially answer questions related to the case study and receive immediate feedback in the form of correct answers and explanations and rationales. Details of the case study, answers, and explanations have been reviewed and approved by NHSN staff. We hope that participants take advantage of this educational offering and thereby gain a greater understanding of NHSN HAI surveillance definitions.

The role of investigative molecular toxicology in early stage drug development.

Molecular toxicology, the application of molecular biology principles and technologies to preclinical safety assessment, represents a key tool for understanding mechanisms of toxicity and assessing the risks associated with specific toxicities. The application of gene expression markers to early stage preclinical safety assessment has the potential to impact pipelines in two main areas: lead optimisation and issue management. Lead optimisation focuses on deprioritising leads with significant, development-limiting toxicological liabilities while advancing those compounds with the greatest chance of successfully navigating the gauntlet of preclinical and clinical safety studies. Issue management utilises mechanistic toxicology studies to position non-development-limiting findings prior to the onset of Good Laboratory Practice studies in full development, and can help to identify and validate gene expression markers predictive of adverse events to avoid issues in second-generation projects. In this review, the authors describe the application of molecular toxicology to a standard pharmaceutical testing funnel, provide examples of the successful application of gene expression markers, and discuss the potential for future impact in several broad categories of clinically relevant toxicity.