Inhibition of the TRAIL death receptor by CMV reveals its importance in NK cell-mediated antiviral defense.

TNF-related apoptosis inducing ligand (TRAIL) death receptors (DR) regulate apoptosis and inflammation, but their role in antiviral defense is poorly understood. Cytomegaloviruses (CMV) encode many immune-modulatory genes that shape host immunity, and they utilize multiple strategies to target the TNF-family cytokines. Here we show that the m166 open reading frame (orf) of mouse CMV (MCMV) is strictly required to inhibit expression of TRAIL-DR in infected cells. An MCMV mutant lacking m166 expression (m166stop) is severely compromised for replication in vivo, most notably in the liver, and depleting natural killer (NK) cells, or infecting TRAIL-DR-/- mice, restored MCMV-m166stop replication completely. These results highlight the critical importance for CMV to have evolved a strategy to inhibit TRAIL-DR signaling to thwart NK-mediated defenses.

Differential B7-CD28 costimulatory requirements for stable and inflationary mouse cytomegalovirus-specific memory CD8 T cell populations.

CMV establishes a lifelong persistent infection, and viral immune-modulating strategies are important in facilitating this. A particularly diverse CD8 T cell response develops as a result of this host-virus détente, with the CMV-specific memory T cell pool displaying unique functions and phenotypes. To gain insight into the factors that regulate CMV-specific CD8 T cell responses, we examined the influence of the B7-CD28 costimulatory pathway on magnitude, kinetics, and phenotype. Initial expansion of mouse CMV-specific CD8 T cells that establish stable memory pools was severely lower in mice lacking B7-CD28 signaling, and the resulting memory levels also remained reduced during persistent/latent infection. In contrast, expansion of CD8 T cells that undergo memory inflation during chronic infection was less affected in the absence of B7-CD28 costimulatory signals, eventually reaching the levels seen in wild-type mice at later times. Regardless of their differential requirements for B7-CD28 signals, both stable and inflationary memory T cell populations showed normal cytotoxic capacity. These results reveal that B7-CD28 costimulation differentially regulates the magnitude and kinetics of the multifaceted CD8 T cell response that develops during CMV infection.

Rates of Preeclampsia and Post-preeclamptic Cardiovascular Disease Among US Military Servicewomen: A Retrospective Case-cohort Study.

INTRODUCTION: Preeclampsia (PE), a hypertensive-inflammatory disorder of pregnancy, poses acute risks of seizures, stroke, and heart attack during pregnancy and up to 6 weeks post-delivery. Recent data suggest that residual increased risks for cardiovascular disease (CVD) linger for much longer, possibly decades, after PE pregnancies. In civilian studies, PE and the major vascular events resulting from it disproportionately affect women from minority groups, especially African American women. The Military Health System (MHS) provides equal access to care for all active-duty servicewomen (ADSW), thus theoretically mitigating disparities. Racial/ethnic breakdown for PE and post PE CVD has not been studied in the MHS. MATERIALS AND METHODS: We identified healthy pregnancies in the MHS electronic health records of ADSW in the years 2009/2010 and those with a PE diagnosis. Patients with preexisting conditions of PE or CVD based on a look-back period of two calendar years were excluded. Cases were matched to controls based on age at pregnancy within 5 years and race/ethnicity. Cohort was assessed for diagnosed CVDs, race, age, and service during 2011-2017. Time to first CVD event was assessed with Cox proportional hazards model, results reported as relative risks (95% CI). All variables were summarized using mean (SD) for normally distributed continuous variables; non-normal continuous variables were characterized by median [IQR] and categorical variables were summarized by counts and frequencies. All statistical testings were two-sided with a significance level of 5% and were completed using SAS-EG version 9.2 or R version 3.5.2. RESULTS: From an analysis of 106,808 inpatient ADSW records, PE incidence by race is 11.8% for White, 12% for African American, 11.4% for Asian/Pacific Islander, 11.2% for Native American, 9.5% for Other, and 7.6% for unknown (not documented) race. Thus, in the US Military, African American women have comparable (0.2% higher) PE rate than White women in contrast with civilian studies that often report much higher incidence in the African American population. Using Asians as referent group, PE increases the risk of CVD. White women have a hazard ratio (HR) of 1.47 95%CI (1.15-1.88), African Americans a HR of 1.51 95% CI (1.18-1.93), and Other a HR of 1.39 95% CI (1.01-1.91). CONCLUSION: In this study, we report overall higher incidence of PE in military women than what is published for civilian women in all races and across all services. Importantly, we do not find significantly higher numbers of PE and post-PE CVD for African American, compared to White women in the military. Our study is not designed to address differences between military and civilian PE epidemiology, but these results deserve further exploration. This study shines light on a health risk unique to women, which we found to be more prevalent in the US Military than published civilian population. Further study to determine the details of long-term morbidity, disability, and death attributable to PE (CVD, stroke, and kidney diseases) are needed to design optimal medical management protocols, ensure readiness for duty, and protect our Women Warfighters.

The mouse cytomegalovirus glycoprotein m155 inhibits CD40 expression and restricts CD4 T cell responses.

Cytomegaloviruses (CMV) utilize a variety of immunomodulatory strategies to facilitate the establishment of lifelong persistence in their infected hosts. We show that the mouse CMV (MCMV) m155 open reading frame (ORF) is required for the posttranscriptional inhibition of CD40 expression in infected antigen-presenting cells. Consistent with the known importance of CD40-mediated costimulation of T cells, a m155-deficient virus induces enhanced MCMV epitope-specific CD4 T cell responses.

B7-mediated costimulation of CD4 T cells constrains cytomegalovirus persistence.

Cytomegalovirus (CMV) utilizes multiple strategies to modulate immunity and promote lifelong, persistent/latent infection, including suppressing T cell activation pathways. Here we examined the role of B7 costimulatory ligands in establishing immune détente from both the host and virus perspectives. Mice lacking both B7.1 and B7.2 showed reduced early expansion of CMV-specific CD4 T cells, consequently allowing for enhanced levels of persistent virus replication. In turn, a CMV mutant lacking expression of the m138 and m147.5 gene products, which restrict B7.1 and B7.2 expression in infected antigen-presenting cells, induced a more robust CD4 T cell response and showed decreased persistence. Together, these data reveal a requirement for B7-mediated signaling in regulating the CMV-specific CD4 T cell response and establishing host-virus equilibrium.

NK cell activation through the NKG2D ligand MULT-1 is selectively prevented by the glycoprotein encoded by mouse cytomegalovirus gene m145.

The NK cell-activating receptor NKG2D interacts with three different cellular ligands, all of which are regulated by mouse cytomegalovirus (MCMV). We set out to define the viral gene product regulating murine UL16-binding protein-like transcript (MULT)-1, a newly described NKG2D ligand. We show that MCMV infection strongly induces MULT-1 gene expression, but surface expression of this glycoprotein is nevertheless completely abolished by the virus. Screening a panel of MCMV deletion mutants defined the gene m145 as the viral regulator of MULT-1. The MCMV m145-encoded glycoprotein turned out to be necessary and sufficient to regulate MULT-1 by preventing plasma membrane residence of MULT-1. The importance of MULT-1 in NK cell regulation in vivo was confirmed by the attenuating effect of the m145 deletion that was lifted after NK cell depletion. Our findings underline the significance of escaping MULT-1/NKG2D signaling for viral survival and maintenance.

Biphasic role of 4-1BB in the regulation of mouse cytomegalovirus-specific CD8(+) T cells.

The initial requirement for the emergence of CMV-specific CD8(+) T cells is poorly understood. Mice deficient in the cosignaling TNF superfamily member, 4-1BB, surprisingly developed exaggerated early CD8(+) T-cell responses to mouse CMV (MCMV). CD8(+) T cells directed against acute MCMV epitopes were enhanced, demonstrating that 4-1BB naturally antagonizes these primary populations. Paradoxically, 4-1BB-deficient mice displayed reduced accumulation of memory CD8(+) T cells that expand during chronic/latent infection. Importantly, the canonical TNF-related ligand, 4-1BBL, promoted the accumulation of these memory CD8(+) T cells, whereas suppression of acute CD8(+) T cells was independent of 4-1BBL. These data highlight the dual nature of the 4-1BB/4-1BBL system in mediating both stimulatory and inhibitory cosignaling activities during the generation of anti-MCMV immunity.

CD4+ T cell help has an epitope-dependent impact on CD8+ T cell memory inflation during murine cytomegalovirus infection.

Murine CMV (MCMV) establishes a systemic, low-level persistent infection resulting in the accumulation of CD8(+) T cells specific for a subset of viral epitopes, a process called memory inflation. Although replicating virus is rarely detected in chronically infected C57BL/6 mice, these inflationary cells display a phenotype suggestive of repeated Ag stimulation, and they remain functional. CD4(+) T cells have been implicated in maintaining the function and/or number of CD8(+) T cells in other chronic infections. Moreover, CD4(+) T cells are essential for complete control of MCMV. Thus, we wondered whether CD4(+) T cell deficiency would result in impaired MCMV-specific CD8(+) T cell responses. Here we show that CD4(+) T cell deficiency had an epitope-specific impact on CD8(+) T cell memory inflation. Of the three codominant T cell responses during chronic infection, only accumulation of the late-appearing IE3-specific CD8(+) T cells was substantially impaired in CD4(+) T cell-deficient mice. Moreover, the increased viral activity did not drive increased CD8(+) T cell division or substantial dysfunction in any MCMV-specific population that we studied. These data show that CD4(+) T cell help is needed for inflation of a response that develops only during chronic infection but is otherwise dispensable for the steady state maintenance and function of MCMV-specific CD8(+) T cells.

Cost of epilepsy-related health care encounters in the United States.

BACKGROUND: The cost of epilepsy is usually reported as total expenditure over a certain period. However, with the increased availability of acute treatments for use in the community setting, intermittent, single-seizure treatment is now possible in addition to the chronic epilepsy drug treatment paradigm. Data on the cost of discrete health care encounters are needed to substantiate the cost-benefit of these new treatments. OBJECTIVE: To estimate the health plan-paid costs of discrete epilepsy-related health care encounters in patients with epilepsy. METHODS: This retrospective cohort study utilized IBM MarketScan Commercial Claims, Medicare Supplemental and Coordination of Benefits (Medicare patients with supplemental insurance), and Multi-State Medicaid research databases. The primary analysis determined health plan-paid cost (adjudicated claims) of discrete epilepsy-related health care encounters, defined as having a primary diagnosis code of epilepsy or convulsion, from 2013 to 2018, in patients with epilepsy aged ≥ 12 years. Costs were adjusted to 2018 prices. Epilepsy cases were defined using ICD-CM codes. We excluded patients on capitated insurance plans as their cost per health care encounter is unknown. RESULTS: In total, 353,530 commercially insured, 378,051 Medicaid, and 69,176 Medicare plus supplemental insurance patients with epilepsy were included. More than 160,000 epilepsy-related emergency transportations, 225,000 emergency department (ED) visits, 49,000 hospitalizations, 700 urgent care visits, and ~2.5 million office visits were analyzed. 37.4% of epilepsy-related hospitalizations included care in the intensive care unit (ICU). In commercially insured patients, epilepsy-related health care encounters had median health plan-paid costs of $22,305 (Q1-Q3 = $14,336-$36,096, hospitalization); $3,375 ($565-$9,095, ICU visit); $1,913 ($417-$4,163, ED visit); $687 ($415-$1,083, emergency transportation); $95 ($23-$232, office visit); and $57 ($0-$171, urgent care visit). The median length of stay for epilepsy-related hospitalizations in working age, commercially insured patients was 4 (Q1-Q3 = 2-5) days. CONCLUSIONS: This is the first study to report health plan-paid cost per epilepsy-related health care encounter. These data can serve as a basis for more granular cost-benefit analyses of not only chronic but also acute treatments of epilepsy. DISCLOSURES: This analysis was funded by UCB Pharma. The sponsor had a role in the identification, design, conduct, and reporting of the analysis. Borghs, Beaty, Boudiaf, and Loewendorf are employees of UCB Pharma. Kalilani and Parekh were employees of UCB Pharma at the time of the analysis. Borghs, Beaty, and Loewendorf have received UCB Pharma stock from their employment. Kalilani and Parekh had received UCB Pharma stock at the time of employment, but no longer hold any. This work was presented in part as a poster at the 73rd Annual Meeting of the American Epilepsy Society; December 7, 2019; Baltimore, MD.

Placental implantation over prior cesarean scar causes activation of fetal regulatory T cells.

INTRODUCTION: Maternal-fetal chimerism is miniscule, a testament to the integrity of the uteroplacental interface. The soundness of this border region is potentially altered through cesarean delivery of prior babies with uncertain consequences for the following pregnancies. METHODS: Using multicolor flow cytometry and quantitative PCR of non-inherited maternal antigens we performed a retrospective case control pilot study and formulated the null hypothesis that placental implantation over a prior uterine scar does not result in the presence of memory Treg (CD45RO+) in the fetus. We then performed a power calculation and performed a blinded, appropriately powered prospective case control study to test the null hypothesis. RESULTS: Fetuses born to mothers with prior uterine scar have a roughly five times higher maternal to fetal microchimerism when the placenta directly interacts with the uterine scar. Unlike exposure to antigens in adult life, in utero antigenic exposure induces tolerogenic (Treg) responses in fetuses and we here report the presence of fetal Treg with a memory phenotype (CD45RO+). However, we only find such CD45RO+ fetal Tregs when the placenta abuts the uterine scar (Risk Ratio = 5 [p < 0.05 CI:(1.448 to 17.27)]). These memory fetal Tregs are functionally highly suppressive compared to CD45RA-expressing fetal Tregs, and have specificity for non-inherited maternal antigens. CONCLUSIONS: We found that uterine scars, in the case of our study these scars are from prior c-sections, fundamentally impair uterine integrity allowing for increased antigen exposure of the fetus; with our appropriately powered study we rejected the null hypothesis and accepted the alternative hypothesis that placental implantation over a prior uterine scar results in the presence of memory Treg (CD45RO+) in the fetus. Thus, our study demonstrates a previously unappreciated role for uterine integrity in limiting fetal antigenic exposure, a key element to avoid the formation of inappropriate tolerances by the fundamentally tolerogenic fetal immune system.

Maternal-Fetal rejection reactions are unconstrained in preeclamptic women.

The risk factors for preeclampsia, extremes of maternal age, changing paternity, concomitant maternal autoimmunity, and/or birth intervals greater than 5 years, suggest an underlying immunopathology. We used peripheral blood and lymphocytes from the UteroPlacental Interface (UPI) of 3rd trimester healthy pregnant women in multicolor flow cytometry-and in vitro suppression assays. The major end-point was the characterization of activation markers, and potential effector functions of different CD4-and CD8 subsets as well as T regulatory cells (Treg). We observed a significant shift of peripheral CD4 -and CD8- T cells from naïve to memory phenotype in preeclamptic women compared to healthy pregnant women consistent with long-standing immune activation. While the proportions of the highly suppressive Cytokine and Activated Treg were increased in preeclampsia, Treg tolerance toward fetal antigens was dysfunctional. Thus, our observations indicate a long-standing inflammatory derangement driving immune activation in preeclampsia; in how far the Treg dysfunction is caused by/causes this immune activation in preeclampsia will be the object of future studies.

Roads Less Traveled: Sexual Dimorphism and Mast Cell Contributions to Migraine Pathology.

Migraine is a common, little understood, and debilitating disease. It is much more prominent in women than in men (~2/3 are women) but the reasons for female preponderance are not clear. Migraineurs frequently experience severe comorbidities, such as allergies, depression, irritable bowel syndrome, and others; many of the comorbidities are more common in females. Current treatments for migraine are not gender specific, and rarely are migraine and its comorbidities considered and treated by the same specialist. Thus, migraine treatments represent a huge unmet medical need, which will only be addressed with greater understanding of its underlying pathophysiology. We discuss the current knowledge about sex differences in migraine and its comorbidities, and focus on the potential role of mast cells (MCs) in both. Sex-based differences in pain recognition and drug responses, fluid balance, and the blood-brain barrier are recognized but their impact on migraine is not well studied. Furthermore, MCs are well recognized for their prominent role in allergies but much less is known about their contributions to pain pathways in general and migraine specifically. MC-neuron bidirectional communication uniquely positions these cells as potential initiators and/or perpetuators of pain. MCs can secrete nociceptor sensitizing and activating agents, such as serotonin, prostaglandins, histamine, and proteolytic enzymes that can also activate the pain-mediating transient receptor potential vanilloid channels. MCs express receptors for both estrogen and progesterone that induce degranulation upon binding. Furthermore, environmental estrogens, such as Bisphenol A, activate MCs in preclinical models but their impact on pain pathways or migraine is understudied. We hope that this discussion will encourage scientists and physicians alike to bridge the knowledge gaps linking sex, MCs, and migraine to develop better, more comprehensive treatments for migraine patients.

Preeclampsia is Characterized by Fetal NK Cell Activation and a Reduction in Regulatory T Cells.

PROBLEM: Preeclampsia affects 3-17% of pregnancies worldwide and has serious consequences for both the mother and the fetus. As maternal-fetal immune tolerance is bidirectional, fetal immunopathology may play a significant role in the pathogenesis of pregnancy disorders. Nevertheless, the impact of preeclampsia on the fetal immune system is unclear. METHOD OF STUDY: In this case-control study, we examined the phenotype of innate and adaptive immune cells from the cord blood of 3rd trimester babies born to healthy mothers and compared them to cord blood from 3rd trimester babies born to mothers with symptomatic preeclampsia. RESULTS: The ratio of CD56hi CD16- non-activated/regulatory NK cells to CD56lo CD16+ activated/effector NK cells as well as the proportion of CD4+ T cells was significantly decreased in the cord blood of babies born to preeclamptic mothers. The percentage of FoxP3+ Treg, especially the FoxP3lo populations (resting Treg and cytokine Treg), were significantly reduced. Importantly, this reduction in FoxP3+ Treg affected the ratio of CD8+ effector T cells per FoxP3+ Treg in the cord blood of babies born to preeclamptic mothers. CONCLUSION: These observations indicate that there are significant fetal immune system derangements during preeclampsia.

Immunological considerations in in utero hematopoetic stem cell transplantation (IUHCT).

In utero hematopoietic stem cell transplantation (IUHCT) is an attractive approach and a potentially curative surgery for several congenital hematopoietic diseases. In practice, this application has succeeded only in the context of Severe Combined Immunodeficiency Disorders. Here, we review potential immunological hurdles for the long-term establishment of chimerism and discuss relevant models and findings from both postnatal hematopoietic stem cell transplantation and IUHCT.

Normal human pregnancy results in maternal immune activation in the periphery and at the uteroplacental interface.

Pregnancy poses a unique challenge to the human immune system: the semi-allogeneic fetus must be protected from maternal immune attack while immunity towards pathogens is maintained. Breakdown in maternal-fetal tolerance can lead to pregnancy-specific diseases with potentially high degrees of morbidity and mortality for both the mother and her fetus. Various immune cell-types could mediate these functions, but a comprehensive evaluation of the peripheral and local maternal T cell and regulatory T cell compartments in normal human pregnancy is lacking. In this case-control study, we apply the Human Immunology Project Consortium proposed gating strategies to samples from healthy 3rd trimester human subjects compared with healthy non-pregnant controls. The proportions of HLA-DR+ and CD38+ effector- and effector memory CD8 T cells are significantly increased in the peripheral blood of pregnant women. Utilizing a novel technique that takes advantage of the standard protocol for intrauterine cleanup after cesarean section, we isolate lymphocytes resident at the uteroplacental interface (UPI). At the UPI, the CD4 and CD8 T cell compartments largely mirror the peripheral blood, except that the proportion of HLA-DR+ activated T regulatory cells is significantly increased in direct proportion to an observed increase in the number of activated CD8 T cells. We find that cryopreservation and delayed sample processing (>12 hours) decreases our ability to identify regulatory T cell subsets. Further, the Consortium proposed method for Treg identification underrepresents Resting and Cytokine Tregs compared with Activated Tregs, thus skewing the entire population. Better understanding of the changes in the immune system during pregnancy in the peripheral blood and at the uteroplacental interface are essential for progress in treatment of pregnancy diseases such as pre-eclampsia and recurrent miscarriage.

Concise review: immunologic lessons from solid organ transplantation for stem cell-based therapies.

Clinical organ transplantation became possible only after powerful immunosuppressive drugs became available to suppress the alloimmune response. After decades of solid organ transplantation, organ rejection is still a major challenge. However, significant insight into allorecognition has emerged from this vast experience and should be used to inform future stem cell-based therapies. For this reason, we review the current understanding of selected topics in transplant immunology that have not been prominent in the stem cell literature, including immune responses to ischemia/reperfusion injuries, natural killer cells, the adaptive immune response, some unresolved issues in T-cell allorecognition, costimulatory molecules, and the anticipated role of regulatory T cells in graft tolerance.

Human cytomegalovirus glycoprotein UL141 targets the TRAIL death receptors to thwart host innate antiviral defenses.

Death receptors (DRs) of the TNFR superfamily contribute to antiviral immunity by promoting apoptosis and regulating immune homeostasis during infection, and viral inhibition of DR signaling can alter immune defenses. Here we identify the human cytomegalovirus (HCMV) UL141 glycoprotein as necessary and sufficient to restrict TRAIL DR function. Despite showing no primary sequence homology to TNF family cytokines, UL141 binds the ectodomains of both human TRAIL DRs with affinities comparable to the natural ligand TRAIL. UL141 binding promotes intracellular retention of the DRs, thus protecting virus infected cells from TRAIL and TRAIL-dependent NK cell-mediated killing. The identification of UL141 as a herpesvirus modulator of the TRAIL DRs strongly implicates this pathway as a regulator of host defense to HCMV and highlights UL141 as a pleiotropic inhibitor of NK cell effector function.

Dissecting the requirements for maintenance of the CMV-specific memory T-cell pool.

Cytomegalovirus (CMV) infection promotes a broad T-cell response, with the resulting memory cells displaying diverse phenotypes. CMV establishes lifelong persistence/latency, and it is thought that viral antigens expressed during this period may regulate the expansion and/or maintenance of "inflationary" CD8 T-memory populations that display an effector memory phenotype. We show here that mouse CMV (MCMV)-specific inflationary memory T cells do not decrease in number after thymectomy, indicating that recent thymic emigrants are not strictly required for their maintenance. Furthermore, persistent MCMV replication in the salivary gland does not significantly impact the T-cell memory compartment, as surgical removal did not alter its composition. These results shed light upon the mechanisms required for maintenance of the large, MCMV-specific T-cell memory pool.

Dendritic cell programming by cytomegalovirus stunts naive T cell responses via the PD-L1/PD-1 pathway.

Early during infection, CMV targets dendritic cells (DC) and alters their functions. Herein we show that CMV-infected DC maintain the ability to present both virus-derived and exogenous Ags, but that they actively induce tolerance or anergy in Ag-specific T cells. CMV accomplishes this by selectively maintaining high-level expression of the negative costimulatory molecule programmed death ligand-1 (PD-L1), while commensurately down-regulating positive costimulatory molecules and MHC on the DC surface. Consequently, CD4 and CD8 T cells activated by these infected DC have a stunted phenotype, characterized by poor proliferation, effector function. and recall responses. Blocking PD-L1, but not PD-L2, during direct priming of naive T cells by infected DC significantly restores Ag-specific T cell functions. Using systems where direct and cross-priming of T cells can be distinguished revealed that PD-L1/PD-1 signaling contributes only when naive T cells are primed directly by infected DC, and not upon cross-presentation of viral Ags by uninfected DC. These data suggest that murine CMV programs infected DC during acute infection to inhibit early host adaptive antiviral responses by tipping the balance between negative and positive cosignals.

Cutting edge: murine cytomegalovirus induces a polyfunctional CD4 T cell response.

CD4 T lymphocytes regulate the adaptive immune response to most viruses, both by providing help to CD8 T cells and B cells as well as through direct antiviral activity. Currently, no mouse cytomegalovirus (MCMV)-specific CD4 T cell responses are known. In this study, we identify and characterize 15 I-A(b)-restricted CD4 T cell responses specific for MCMV epitopes. CD4 T cells accumulate to high levels in the spleen and lungs during acute infection and produce multiple cytokines (IFN-gamma, TNF, IL-2, IL-10, and IL-17). Interestingly, IL-17 and IFN-gamma production within epitope-specific cells was found to be mutually exclusive. CD4 T cells recognizing a peptide derived from m09 were only detectable at later times of infection and displayed a unique cytokine production profile. In total, this study reveals that the MCMV-specific CD4 T cell response is complex and functionally diverse, highlighting its important role in controlling this persistent pathogen.