Frequency of CXCR3+ CD8+ T-Lymphocyte Subsets in Peripheral Blood Is Associated With the Risk of Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome Development in Advanced HIV Disease

Background

Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a clinical aggravation of TB symptoms observed among a fraction of HIV coinfected patients shortly after the start of antiretroviral therapy (ART). Of note, TB-IRIS is characterized by exacerbated inflammation and tissue damage that occurs in response to the elevated production of CD4+ T cell-derived IFN-γ. Nevertheless, the possible participation of CD8+ T cells in TB-IRIS development remains unclear.

Methods

We performed a comprehensive assessment of the composition of CD8+ T cell memory subsets and their association with circulating inflammation-related molecules in TB-HIV coinfected patients initiating ART.

Results

We found that TB-IRIS individuals display higher frequencies of Antigen-experienced CD8+ T cells during the onset of IRIS and that the levels of these cells positively correlate with baseline mycobacterial smear grade. TB-IRIS individuals exhibited higher frequencies of effector memory and lower percentages of naïve CD8+ T cells than their Non-IRIS counterparts. In both TB-IRIS and Non-IRIS patients, ART commencement was associated with fewer significant correlations among memory CD8+ T cells and cells from other immune compartments. Networks analysis revealed distinct patterns of correlation between each memory subset with inflammatory cytokines suggesting different dynamics of CD8+ T cell memory subsets reconstitution. TB-IRIS patients displayed lower levels of memory cells positive for CXCR3 (a chemokine receptor that plays a role in trafficking activated CD8+ T cells to the tissues) than Non-IRIS individuals before and after ART. Furthermore, we found that CXCR3+ naïve CD8+ T cells were inversely associated with the risk of TB-IRIS development. On the other hand, we noticed that the frequencies of CXCR3+ effector CD8+ T cells were positively associated with the probability of TB-IRIS development.

Conclusion

Our data suggest that TB-IRIS individuals display a distinct profile of memory CD8+ T cell subsets reconstitution after ART initiation. Moreover, our data point to a differential association between the frequencies of CXCR3+ CD8+ T cells and the risk of TB-IRIS development. Collectively, our findings lend insights into the potential role of memory CD8+ T cells in TB-IRIS pathophysiology.

Dynamics of T-Lymphocyte Activation Related to Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome in Persons With Advanced HIV

Most persons living with HIV (PLWH) experience a significant restoration of their immunity associated with successful inhibition of viral replication after antiretroviral therapy (ART) initiation. Nevertheless, with the robust quantitative and qualitative restoration of CD4⁺ T-lymphocytes, a fraction of patients co-infected with tuberculosis develop immune reconstitution inflammatory syndrome (TB-IRIS), a dysregulated inflammatory response that can be associated with significant tissue damage. Several studies underscored the role of adaptive immune cells in IRIS pathogenesis, but to what degree T lymphocyte activation contributes to TB-IRIS development remains largely elusive. Here, we sought to dissect the phenotypic landscape of T lymphocyte activation in PLWH coinfected with TB inititating ART, focusing on characterization of the profiles linked to development of TB-IRIS. We confirmed previous observations demonstrating that TB-IRIS individuals display pronounced CD4⁺ lymphopenia prior to ART initiation. Additionally, we found an ART-induced increase in T lymphocyte activation, proliferation and cytotoxicity among TB-IRIS patients. Importantly, we demonstrate that TB-IRIS subjects display higher frequencies of cytotoxic CD8⁺ T lymphocytes which is not affected by ART. Moreover, These patients exhibit higher levels of activated (HLA-DR⁺) and profilerative (Ki-67⁺) CD4⁺ T cells after ART commencenment than their Non-IRIS counterparts. Our network analysis reveal significant negative correlations between Total CD4⁺ T cells counts and the frequencies of Cytotoxic CD8⁺ T cells in our study population which could suggest the existance of compensatory mechanisms for Mtb-infected cells elimination in the face of severe CD4⁺ T cell lymphopenia. We also investigated the correlation between T lymphocyte activation profiles and the abundance of several inflammatory molecules in plasma. We applied unsupervised machine learning techniques to predict and diagnose TB-IRIS before and during ART. Our analyses suggest that CD4⁺ T cell activation markers are good TB-IRIS predictors, whereas the combination of CD4⁺ and CD8⁺ T cells markers are better at diagnosing TB-IRIS patients during IRIS events Overall, our findings contribute to a more refined understanding of immunological mechanisms in TB-IRIS pathogenesis that may assist in new diagnostic tools and more targeted patient management.

Secukinumab in non-radiographic axial spondyloarthritis: subgroup analysis based on key baseline characteristics from a randomized phase III study, PREVENT

BACKGROUND

To investigate the efficacy of secukinumab in patients with active non-radiographic axial spondyloarthritis (nr-axSpA) grouped by disease activity as assessed by C-reactive protein (CRP) levels and/or magnetic resonance imaging (MRI) scores, human leukocyte antigen (HLA)-B27 status, and sex.

METHODS

The phase III PREVENT study randomized (1:1:1) 555 patients to receive subcutaneous secukinumab 150 mg with (LD) or without (NL) loading dose or placebo weekly, followed by every 4 weeks starting at week 4. Here, we report the results of a post hoc analysis reporting the efficacy outcomes (pooled secukinumab) to 16 weeks by CRP, MRI, HLA-B27, and sex.

RESULTS

Efficacy differences between the secukinumab and the placebo groups were highest in the CRP+, MRI+, HLA-B27+, and male subgroups, particularly for Ankylosing Spondylitis Disease Activity Score-CRP inactive disease and Assessment of SpondyloArthritis international Society (ASAS) partial remission outcomes. ASAS40 response rates in the CRP+/MRI+ subgroup was 52.3% (secukinumab) versus 21.8% (placebo; P < 0.0001) at week 16. ASAS40 response rates (secukinumab versus placebo) were 43.9% versus 32.6% in HLA-B27+, 32.7% versus 16.4% in HLA-B27- subgroups, 51.2% versus 30.8% in male, and 31.7% versus 25.3% in female patients, respectively.

CONCLUSIONS

Secukinumab improved the signs and symptoms of nr-axSpA across patients grouped by CRP (+/-) and/or MRI (+/-) status, HLA-B27 (+/-) status, and sex. The highest treatment differences between secukinumab and placebo were observed in patients with both elevated CRP and evidence of sacroiliitis on MRI. Treatment difference was minimal between HLA-B27 (+) and (-) subgroups. Male patients had higher relative responses than female patients.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT02696031 . Registered on 02 March 2016.

Improvement of Signs and Symptoms of Nonradiographic Axial Spondyloarthritis in Patients Treated With Secukinumab: Primary Results of a Randomized, Placebo-Controlled Phase III Study

Objective

To report the primary (1‐year) results from PREVENT, the first phase III study evaluating secukinumab in patients with active nonradiographic axial spondyloarthritis (SpA).

Methods

A total of 555 patients were randomized (1:1:1) to receive subcutaneous secukinumab 150 mg with a loading dose (loading dose [LD] group), secukinumab 150 mg without a loading dose (non–loading dose [NL] group), or placebo weekly and then every 4 weeks starting at week 4. The NL group received placebo at weeks 1, 2, and 3 to maintain blinding. Switch to open‐label secukinumab or standard of care was permitted after week 20. The study had 2 independent analysis plans, per European Union and non‐US (plan A; week 16) and US (plan B; week 52) regulatory requirements. The primary end point was 40% improvement in disease activity according to the Assessment of SpondyloArthritis international Society (ASAS40) criteria at week 16 (in the LD group) and at week 52 (in the NL group) in tumor necrosis factor inhibitor (TNFi)–naive patients. Safety analyses included all patients who received ≥1 dose of study treatment.

Results

Overall, 481 patients completed 52 weeks of treatment, including 84.3% (156 of 185) in the LD group, 89.7% (165 of 184) in the NL group, and 86.0% (160 of 186) in the placebo group. The proportion of patients who switched to open‐label or standard of care between weeks 20 and 48 was 50.8% in the LD group, 47.3% in the NL group, and 64.0% in the placebo group. Both primary and all secondary end points were met at week 16. The proportion of TNFi‐naive patients who met ASAS40 was significantly higher for LD at week 16 (41.5%) and NL at week 52 (39.8%) versus placebo (29.2% at week 16 and 19.9% at week 52; both P < 0.05). No new safety findings were reported.

Conclusion

Our findings indicate that secukinumab 150 mg provides significant and sustained improvement in signs and symptoms of nonradiographic axial SpA through 52 weeks. Safety was consistent with previous reports.

Secukinumab 150/300 mg Provides Sustained Improvements in the Signs and Symptoms of Active Ankylosing Spondylitis: 3-Year Results from the Phase 3 MEASURE 3 Study

Objective

Secukinumab 150 mg has demonstrated significant improvement in signs and symptoms of ankylosing spondylitis (AS), with response rates sustained for up to 5 years. Here, we report end‐of‐study 3‐year efficacy and safety results of secukinumab 150 and 300 mg from the MEASURE 3 study.

Methods

A total of 226 patients was randomized to intravenous secukinumab 10 mg/kg (baseline, weeks 2 and 4) followed by subcutaneous (s.c.) secukinumab 300/150 mg every 4 weeks or a matched placebo. At week 16, placebo patients were re‐randomized to s.c. secukinumab 300/150 mg. Analysis at week 156 included patients initially randomized to secukinumab and those who switched from placebo to secukinumab at week 16 (any secukinumab 300/150 mg). Outcome measures at week 156 included Assessment of Spondyloarthritis International Society (ASAS) 20/40, Bath Ankylosing Spondylitis Disease Activity Index, ASAS partial remission (PR), ASAS 5/6, and Ankylosing Spondylitis Disease Activity Score–C‐reactive protein inactive disease.

Results

The retention rates from weeks 16 to 156 were 80.5% and 80.9% in secukinumab 300 and 150 mg, respectively. ASAS 20/40 response rates at week 156 were 75.0%/56.5% and 68.2%/47.7% for secukinumab 300 and 150 mg, respectively. At week 156, response rates on more stringent clinical end points (eg, ASAS 40, ASAS‐PR) were higher with the 300‐mg dose, particularly in tumor necrosis factor (TNF)–inadequate responder (IR) patients. No new safety findings were observed.

Conclusion

Secukinumab (300 and 150 mg) provided sustained improvements through 3 years in the signs and symptoms of active AS. Improvements with secukinumab 300 mg were numerically higher compared with the 150‐mg dose for some higher hurdle end points and in TNF‐IR patients. The safety profile of secukinumab was consistent with previous reports.

Differential expression of CXCR3 and CCR6 on CD4+ T-lymphocytes with distinct memory phenotypes characterizes tuberculosis-associated immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) occurs in up to 40% of individuals co-infected with pulmonary tuberculosis (PTB) and HIV, primarily upon antiretroviral therapy (ART) initiation. Phenotypic changes in T-cells during TB-IRIS and their relationship with systemic inflammation are not fully understood. In this prospective cohort study, we followed 48 HIV-positive patients with PTB from South India before and after ART initiation, examining T-lymphocyte subsets and inflammatory biomarkers in peripheral blood. Quantification of naïve (CD27⁺CD45RO^-) as well as effector memory CD4⁺ T cells (CD27^-CD45RO⁺) at weeks 2-6 after ART initiation could distinguish TB-IRIS from non-IRIS individuals. Additional analyses revealed that ART reconstituted different quantities of CD4⁺ T lymphocyte subsets with preferential expansion of CXCR3⁺ CCR6^- cells in TB-IRIS patients. Moreover, there was an expansion and functional restoration of central memory (CD27⁺CD45RO⁺) CXCR3⁺CCR6^- CD4⁺ lymphocytes and corresponding cytokines, with reduction in CXCR3^-CCR6⁺ cells after ART initiation only in those who developed TB-IRIS. Together, these observations trace a detailed picture of CD4⁺ T cell subsets tightly associated with IRIS, which may serve as targets for prophylactic and/or therapeutic interventions in the future.

Blended Infant Massage-Parenting Enhancement Program on Recovering Substance-Abusing Mothers' Parenting Stress, Self-Esteem, Depression, Maternal Attachment, and Mother-Infant Interaction

PURPOSE

This study aimed to determine whether a blended Infant Massage-Parenting Enhancement Program (IMPEP) improved maternal psychosocial health outcomes (parenting stress, depressive symptoms, self-esteem, maternal attachment) and maternal-infant interaction among substance-addicted mothers (SAMs) actively engaged in outpatient rehabilitation.

METHODS

Designed as a randomized, three-group controlled trial testing two levels of psychoeducational intervention (IMPEP vs. PEP) and a control group (standard care parenting resources), the study was conducted in two substance abuse centers in southeast Florida on a convenience sample of 138 recovering SAM-infant pairs. IMPEP or PEP classes were held weekly on Weeks 2-5, with data collected at baseline (Week 1), Week 6, and Week 12 via structured interviews, observation (Observation Checklist on Maternal-Infant Interaction), and self-administered questionnaires (Abidin Parenting Stress Index, Beck Depression Inventory, Rosenberg Self-Esteem Scale, Muller's Maternal Attachment Inventory), analyzed descriptively and inferentially using Kruskall-Wallis analysis of variance and post hoc Wilcoxon rank sum and Mann-Whitney U tests.

RESULTS

Both IMPEP and PEP groups had significantly increased Parenting Stress Index scores (decreased parenting stress) and decreased Beck Depression Inventory scores (decreased depressive symptoms) compared to controls at Week 12, whereas there were no clinically meaningful differences among study groups in Rosenberg Self-Esteem Scale, Muller's Maternal Attachment Inventory, or Observation Checklist on Maternal-Infant Interaction scores. Only the IMPEP group showed significant improvements in both psychological and physical (waist-hip ratio) measures of parenting stress over time.

CONCLUSIONS

The findings suggest that infant massage blended into a structured parenting program has value-added effects in decreasing parenting stress and maternal depressive symptoms, but not on SAM's self-esteem, attachment, or maternal-infant interaction.

Mycobacterial antigen driven activation of CD14++CD16- monocytes is a predictor of tuberculosis-associated immune reconstitution inflammatory syndrome

Paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is an aberrant inflammatory response occurring in a subset of TB-HIV co-infected patients initiating anti-retroviral therapy (ART). Here, we examined monocyte activation by prospectively quantitating pro-inflammatory plasma markers and monocyte subsets in TB-HIV co-infected patients from a South Indian cohort at baseline and following ART initiation at the time of IRIS, or at equivalent time points in non-IRIS controls. Pro-inflammatory biomarkers of innate and myeloid cell activation were increased in plasma of IRIS patients pre-ART and at the time of IRIS; this association was confirmed in a second cohort in South Africa. Increased expression of these markers correlated with elevated antigen load as measured by higher sputum culture grade and shorter duration of anti-TB therapy. Phenotypic analysis revealed the frequency of CD14⁺⁺CD16⁻ monocytes was an independent predictor of TB-IRIS, and was closely associated with plasma levels of CRP, TNF, IL-6 and tissue factor during IRIS. In addition, production of inflammatory cytokines by monocytes was higher in IRIS patients compared to controls pre-ART. These data point to a major role of mycobacterial antigen load and myeloid cell hyperactivation in the pathogenesis of TB-IRIS, and implicate monocytes and monocyte-derived cytokines as potential targets for TB-IRIS prevention or treatment.

Tuberculosis and HIV majorly impact host immune responses, resulting in immune deregulation and inflammation-driven tissue damage. Initiation of anti-retroviral therapy in patients with HIV-TB co-infection may result in immune reconstitution inflammatory syndrome (TB-IRIS), a disorder associated with increased immunopathology due to unfettered inflammation after CD4⁺ T-cell reconstitution. Monocytes are critical to the innate immune system and play an important role in several inflammatory conditions associated with chronic infections. Immunopathogenesis of TB-IRIS has been linked to activation of the adaptive immune response against opportunistic infection, yet the role of monocytes is still unknown. Here we investigated associations between soluble markers of monocyte activation, differential activation of monocyte subsets and TB-IRIS prospectively in two geographically distinct HIV-TB co-infected patient cohorts. Prior to ART initiation, patients who developed IRIS displayed a biosignature of elevated soluble monocyte activation markers, which were closely related to the mycobacterial antigen load in sputum samples. Amongst monocyte subsets, we observed that pre-ART circulating CD14⁺⁺CD16⁻ cell frequency independently predicted TB-IRIS and expanded during IRIS events. This monocyte subset was tightly associated with systemic markers of inflammation, and was found to produce inflammatory cytokines. Identification of this monocyte subset and its link with inflammation may lead to conception of novel therapies reducing immunopathology in TB-IRIS.

Paradoxical tuberculosis immune reconstitution inflammatory syndrome (TB-IRIS) in HIV patients with culture confirmed pulmonary tuberculosis in India and the potential role of IL-6 in prediction

Background

The incidence, manifestations, outcome and clinical predictors of paradoxical TB-IRIS in patients with HIV and culture confirmed pulmonary tuberculosis (PTB) in India have not been studied prospectively.

Methods

HIV+ patients with culture confirmed PTB started on anti-tuberculosis therapy (ATT) were followed prospectively after anti-retroviral therapy (ART) initiation. Established criteria for IRIS diagnosis were used including decline in plasma HIV RNA at IRIS event. Pre-ART plasma levels of interleukin (IL)-6 and C-reactive protein (CRP) were measured. Univariate and multivariate logistic regression models were used to evaluate associations between baseline variables and IRIS.

Results

Of 57 patients enrolled, 48 had complete follow up data. Median ATT-ART interval was 28 days (interquartile range, IQR 14–47). IRIS events occurred in 26 patients (54.2%) at a median of 11 days (IQR: 7–16) after ART initiation. Corticosteroids were required for treatment of most IRIS events that resolved within a median of 13 days (IQR: 9–23). Two patients died due to CNS TB-IRIS. Lower CD4⁺ T-cell counts, higher plasma HIV RNA levels, lower CD4/CD8 ratio, lower hemoglobin, shorter ATT to ART interval, extra-pulmonary or miliary TB and higher plasma IL-6 and CRP levels at baseline were associated with paradoxical TB-IRIS in the univariate analysis. Shorter ATT to ART interval, lower hemoglobin and higher IL-6 and CRP levels remained significant in the multivariate analysis.

Conclusion

Paradoxical TB–IRIS frequently complicates HIV-TB therapy in India. IL-6 and CRP may assist in predicting IRIS events and serve as potential targets for immune interventions.

Elevated frequencies of highly activated CD4+ T cells in HIV+ patients developing immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) is a considerable problem in the treatment of HIV-infected patients. To identify immunologic correlates of IRIS, we characterized T-cell phenotypic markers and serum cytokine levels in HIV patients with a range of different AIDS-defining illnesses, before and at regular time points after initiation of antiretroviral therapy. Patients developing IRIS episodes displayed higher frequencies of effector memory, PD-1(+), HLA-DR(+), and Ki67(+) CD4(+) T cells than patients without IRIS. Moreover, PD-1(+) CD4(+) T cells in IRIS patients expressed increased levels of LAG-3, CTLA-4, and ICOS and had a Th1/Th17 skewed cytokine profile upon polyclonal stimulation. Elevated PD-1 and Ki67 expression was also seen in regulatory T cells of IRIS patients. Furthermore, IRIS patients displayed higher serum interferon-γ, compared with non-IRIS patients, near the time of their IRIS events and higher serum interleukin-7 levels, suggesting that the T-cell populations are also exposed to augmented homeostatic signals. In conclusion, our findings indicate that IRIS appears to be a predominantly CD4-mediated phenomenon with reconstituting effector and regulatory T cells showing evidence of increased activation from antigenic exposure. These studies are registered online at http://clinicaltrials.gov as NCT00557570 and NCT00286767.

d-Dimer and CRP levels are elevated prior to antiretroviral treatment in patients who develop IRIS

Biomarkers could be useful in evaluating immune reconstitution inflammatory syndrome (IRIS). A cohort of 45 HIV-1-infected, antiretroviral treatment (ART)-naive patients with baseline CD4 T cell counts <or=100 cells/microL who were started on ART, suppressed HIV-RNA to <50 copies/mL, and seen every 1-3 months for 1 year were retrospectively evaluated for suspected or confirmed IRIS. d-Dimer, C-reactive protein (CRP), and selected autoantibodies were analyzed at baseline, 1 and 3 months post-ART in cryopreserved plasma. Median differences between cases and controls were compared with Mann-Whitney and Fisher's exact tests. Sixteen patients (35.6%) developed IRIS (median of 35 days post-ART initiation): unmasking=8, paradoxical=7, autoimmune=1. Pre-ART d-dimer and CRP were higher in IRIS cases versus controls (d-dimer: 0.89 mg/L versus 0.66 mg /L, p=0.037; CRP: 0.74 mg/L versus 0.39 mg/L, p=0.022), while d-dimer was higher in unmasking cases at IRIS onset (2.04 mg/L versus 0.36 mg /L, p=0.05). These biomarkers may be useful in identifying patients at risk for IRIS.

Cardiac troponin T and cardiac dysfunction in extremely low-birth-weight infants

Extremely low-birth-weight (ELBW) infants frequently manifest signs of cardiac dysfunction requiring inotropic support. It is not clear if this is due to cardiac injury, which can be monitored by measuring cardiac troponin T (cTnT). We performed a nested prospective cohort study at a university level III neonatal intensive care unit. The study included 27 infants weighing between 500 and 999 g. Exclusion criteria included evidence of sepsis, use of postnatal steroids, and cardiac anomalies. Measurements included serum cTnT and echocardiogram in the first 48 hours of life. The mean serum cTnT level of the study population was 0.52 +/- 0.38 ng/ml. It was higher in those with lower Apgar scores (0.89 +/- 0.37 if 5-minute Apgar < 4 vs 0.36 +/- 0.26 ng/ml, p < 0.001) and correlated to initial base deficit (r = -0.37, p < 0.05). Infants who required inotropic support had higher cTnT levels than those who did not (0.73 +/- 0.43 vs 0.39 +/- 0.29 ng/ml, p < 0.03). cTnT concentrations did not relate to simultaneous echocardiographic measures of cardiac function. In ELBW infants, serum cTnT levels are higher than normally seen in term infants and adults, and they are higher in infants with greater perinatal stress as well as those who show evidence of cardiac dysfunction requiring pressor support.

A blended infant massage--parenting enhancement program for recovering substance-abusing mothers

Interventions that build upon the natural components of early mother-infant interactions are critical to reversing the sequelae of maternal substance abuse and breaking the cycle of addiction. This paper proposes a theoretical model that blends infant massage (IM) into a planned parenting enhancement program (PEP) to promote improved health outcomes in recovering substance- abusing mothers (SAMs) and their babies. With 4.6 million women of child-bearing age regularly using cocaine in the United States and 750,000 drug-exposed births annually, maternal substance abuse highlights the multigenerational impact of drug use in high-risk populations and its risks to our children. The proposed IMPEP model provides a means to assist recovering SAMs in making cognitive-behavioral changes through new knowledge about parenting and parenting skills, with a special focus on infant stimulation via massage. The goal is to enable recovering SAMs to become confident and responsive mothers, empowering them to become effective parents. Pilot data suggest the Infant Massage Parenting Enhancement Program (IMPEP) is effective for both mother and infant, and merits a controlled systematic study.

Current opinion regarding indications for emergency department thoracotomy

BACKGROUND

Emergency department thoracotomy (EDT) is a dramatic but rarely lifesaving intervention. Clinical variability regarding indications for EDT has yet to be quantified. Members of the Eastern and American Associations for the Surgery of Trauma were questioned by mail to evaluate which clinical and demographic factors influence the decision to perform EDT and whether physicians perform EDT in accordance with current practice guidelines.

METHODS

A single mailing of an anonymous survey was sent to 1,124 surgeons to collect institutional and physician demographics as well as indications for EDT on the basis of variable mechanisms of trauma, duration of arrest, and signs of life (SOL). Statistical analysis included the Pearson and linear-by-linear association chi(2) tests, independent samples t test, and univariate and multivariate analyses of variance; p values of < 0.05 were considered significant.

RESULTS

Completed surveys were received from 358 respondents. After 54 surveys were excluded that were incomplete, late, or from noneligible respondents, 304 surveys were analyzed. There were no significant differences in EDT indications among institutions of differing caseload volume, exposure to penetrating trauma, trauma level designation, American College of Surgeons verification status, or residency program affiliation. In addition, neither the respondent's position nor whether attendings versus residents performed the majority of EDTs influenced clinical decision-making. Performance criteria for EDT were liberal in comparison with established guidelines, especially for blunt trauma. The presence or recent loss of SOL influenced responses, but respondents varied greatly in their definition of SOL.

CONCLUSION

A lack of agreement exists regarding the indications for EDT in multiple clinical scenarios as well as in defining SOL. Indications for EDT were liberal, especially for blunt trauma-related indications, and were determined by clinical parameters, not by physician or institutional factors. Our results suggest that clinical practice is at variance with Advanced Trauma Life Support guidelines. We recommend that practice guidelines for EDT be established on the basis of a consensus definition of SOL to allow for a more uniform and selective approach to EDT.

Control of T cell development in vivo by subdomains within the IL-7 receptor alpha-chain cytoplasmic tail

IL-7/IL-7R signaling functions in both growth and differentiation during T cell development. In this study, we examined the extent these activities were controlled by signaling associated with distinct IL-7R alpha cytoplasmic domains by transgenic expression of wild-type or cytoplasmic deletion mutants of IL-7R alpha in the thymi of IL-7R alpha(-/-) mice. We show an essential requirement for the tyrosine-containing carboxyl-terminal T domain in restoring thymic cellularity, pro-/pre-T cell progression, and survival. In contrast, the functional differentiation of TCR alpha beta cells and the development of TCR gamma delta cells are partially independent of the T domain. Thus, separate cytoplasmic domains of the IL-7R alpha chain differentially control distinct functions during T cell development, whereas normal IL-7R-dependent thymic development requires the integrated activity of all these domains.

Thymic and intestinal intraepithelial T lymphocyte development are each regulated by the gammac-dependent cytokines IL-2, IL-7, and IL-15

Both thymic and extrathymic T lineage development are characterized by cytokine-dependent regulation of complex proliferative, differentiative, and anti-apoptotic processes. The role of the gammac-dependent cytokines in this program has been interpreted as limited to the activity of IL-7. However, through the analysis of double knock-out mice, which lack signaling through the IL-7R and other gammac-dependent cytokines, we revealed a role for IL-15 in the production of early thymic pro-T cells. Although IL-2 does not function in the production of thymocytes, thymic restoration of IL-2R expression prevented fatal autoimmunity associated with IL-2- or IL-2R-deficient mice, suggesting that IL-2R functions non-redundantly at the level of the thymus to regulate self-reactivity. Moreover, IL-2, IL-7, and IL-15 also extend their developmental effects beyond the thymus to other sites of T lymphocyte production, including the gut. Here, their redundant and non-redundant activities are directly correlated to the development of phenotypically diverse subsets of intestinal intraepithelial lymphocytes.

Normal lymphoid homeostasis and lack of lethal autoimmunity in mice containing mature T cells with severely impaired IL-2 receptors

The importance of IL-2Rbeta function for immune regulation is highlighted by the severe impairment in lymphoid cell function in IL-2Rbeta-deficient mice. It has been speculated that failed IL-2/IL-2R signaling in peripheral T cells causes the associated autoimmunity, imbalanced peripheral lymphoid homeostasis, and defective T cell function. This study explored the requirement for IL-2Rbeta function in mature T lymphocytes. We show that transgenic thymic expression of the IL-2R beta-chain in IL-2Rbeta-deficient mice prevents lethal autoimmunity, restores normal production of B lymphocytes, and results in a peripheral T cell compartment that is responsive to triggering through the TCR, but not the IL-2R. The dysfunction of the IL-2R is illustrated by the near complete failure of mature T cells to proliferate to IL-2 in vitro and in vivo, to differentiate into CTL, and to up-regulate IL-2Ralpha expression. These data indicate that lymphoid homeostasis is largely maintained despite a nonfunctional IL-2R in mature T lymphocytes and suggest that IL-2Rbeta provides an essential signal during thymic development to regulate self-reactivity.

IL-2Rbeta/IL-7Ralpha doubly deficient mice recapitulate the thymic and intraepithelial lymphocyte (IEL) developmental defects of gammac-/- mice: roles for both IL-2 and IL-15 in CD8alphaalpha IEL development

IL-7Ralpha-chain-deficient (IL-7Ralpha-/-) and common gamma chain-deficient (gammac-/-) mice both exhibit abnormal thymic and intestinal intraepithelial lymphocyte (IEL) development, but the developmental inhibition is not equivalent. In this report, we assessed whether the defects in T cell development associated with gammac-/- mice were due to currently defined gammac-dependent cytokines by cross-breeding IL-7Ralpha-/- mice to mice lacking either IL-2, IL-4, or IL-2Rbeta. IL-2/IL-7Ralpha and IL-4/IL-7Ralpha double knockout (DKO) mice demonstrated equivalent thymic development to IL-7Ralpha-/- mice, whereas IL-2Rbeta/IL-7Ralpha DKO mice, which lack IL-2, IL-7, and IL-15 signaling, displayed thymic T cell defects identical to gammac-/- mice. Collectively, these data indicate that of the gammac-dependent cytokines, only IL-7 and IL-15 contribute to the progression and production of thymic T cells. In the IEL, IL-7Ralpha-/- mice selectively lack CD8alphaalpha TCRgammadelta cells, whereas IL-2Rbeta-/- mice show a significant reduction in all CD8alphaalpha cells. IL-2-/- and IL-2/IL-7Ralpha DKO mice demonstrated a reduction in CD8alphaalpha IELs to nearly the same extent as IL-2Rbeta-/- mice, indicating that IL-2 functions in CD8alphaalpha IEL development. Moreover, IL-2Rbeta/IL-7Ralpha DKO mice lacked nearly all TCR-bearing IEL, again recapitulating the phenotype of gammac-/- mice. Thus, these data point to the importance of IL-2, IL-7, and IL-15 as the gammac-dependent cytokines essential for IEL development.

IL-2Rβ/IL-7Rα Doubly Deficient Mice Recapitulate the Thymic and Intraepithelial Lymphocyte (IEL) Developmental Defects of γc−/− Mice: Roles for Both IL-2 and IL-15 in CD8αα IEL Development

IL-7Rα-chain-deficient (IL-7Rα−/−) and common γ chain-deficient (γc−/−) mice both exhibit abnormal thymic and intestinal intraepithelial lymphocyte (IEL) development, but the developmental inhibition is not equivalent. In this report, we assessed whether the defects in T cell development associated with γc−/− mice were due to currently defined γc-dependent cytokines by cross-breeding IL-7Rα−/− mice to mice lacking either IL-2, IL-4, or IL-2Rβ. IL-2/IL-7Rα and IL-4/IL-7Rα double knockout (DKO) mice demonstrated equivalent thymic development to IL-7Rα−/− mice, whereas IL-2Rβ/IL-7Rα DKO mice, which lack IL-2, IL-7, and IL-15 signaling, displayed thymic T cell defects identical to γc−/− mice. Collectively, these data indicate that of the γc-dependent cytokines, only IL-7 and IL-15 contribute to the progression and production of thymic T cells. In the IEL, IL-7Rα−/− mice selectively lack CD8αα TCRγδ cells, whereas IL-2Rβ−/− mice show a significant reduction in all CD8αα cells. IL-2−/− and IL-2/IL-7Rα DKO mice demonstrated a reduction in CD8αα IELs to nearly the same extent as IL-2Rβ−/− mice, indicating that IL-2 functions in CD8αα IEL development. Moreover, IL-2Rβ/IL-7Rα DKO mice lacked nearly all TCR-bearing IEL, again recapitulating the phenotype of γc−/− mice. Thus, these data point to the importance of IL-2, IL-7, and IL-15 as the γc-dependent cytokines essential for IEL development.

Prostaglandin E2 inhibits T cell activation-induced apoptosis and Fas-mediated cellular cytotoxicity by blockade of Fas-ligand induction

Prostanoids exhibit both pro-apoptotic and anti-apoptotic functions depending on the maturation stage and tissue localization of target cells. Prostaglandin (PG) E2 has been shown to protect T lymphocytes from TCR-mediated activation-induced cell death, but the mechanism by which PGE2 inhibits apoptosis of T cells has not been established. We show that this protection involves the down-regulation of Fas-ligand (Fas-L) mRNA levels in T cells. Modulation of cell surface Fas-L expression by physiological concentrations of PGE2 was shown to be both anti-apoptotic as well as capable of inhibiting Fas-L-mediated cytotoxicity of Fas-transfected P815 target cells. Thus, this study provides direct evidence of the likely biological means by which PGE2 down-regulates T cell apoptosis.

Multiple gamma c-dependent cytokines regulate T-cell development

Mutations in the common gamma chain (gamma c) of cytokine receptors account for human X-linked severe combined immunodeficiency disease. gamma c contributes to ligand binding and signaling as a component of five cytokine receptors: interleukin-2-receptor (IL-2R), IL-4R, IL-7R, IL-9R and IL-15R. Here, Thomas Malek and colleagues discuss the contribution of individual gamma c-dependent cytokines in both conventional and intraepithelial T-cell development.