The TCF1-Bcl6 axis counteracts type I interferon to repress exhaustion and maintain T cell stemness

During chronic viral infections and in cancer, T cells become dysfunctional, a state known as T cell exhaustion. Although it is well recognized that memory CD8 T cells account for the persistence of CD8 T cell immunity after acute infection, how exhausted T cells persist remains less clear. Using chronic infection with lymphocytic choriomeningitis virus clone 13 and tumor samples, we demonstrate that CD8 T cells differentiate into a less exhausted TCF1^high and a more exhausted TCF1^low population. Virus-specific TCF1^high CD8 T cells, which resemble T follicular helper (T_FH) cells, persist and recall better than do TCF1^low cells and act as progenitor cells to replenish TCF1^low cells. We show that TCF1 is both necessary and sufficient to support this progenitor-like CD8 subset, whereas cell-intrinsic type I interferon signaling suppresses their differentiation. Accordingly, cell-intrinsic TCF1 deficiency led to a loss of these progenitor CD8 T cells, sharp contraction of virus-specific T cells, and uncontrolled viremia. Mechanistically, TCF1 repressed several pro-exhaustion factors and induced Bcl6 in CD8 T cells, which promoted the progenitor fate. We propose that the TCF1-Bcl6 axis counteracts type I interferon to repress T cell exhaustion and maintain T cell stemness, which is critical for persistent antiviral CD8 T cell responses in chronic infection. These findings provide insight into the requirements for persistence of T cell immune responses in the face of exhaustion and suggest mechanisms by which effective T cell-mediated immunity may be enhanced during chronic infections and cancer.

CD8+ T cells target cerebrovasculature in children with cerebral malaria

BACKGROUNDCerebral malaria (CM) accounts for nearly 400,000 deaths annually in African children. Current dogma suggests that CM results from infected RBC (iRBC) sequestration in the brain microvasculature and resulting sequelae. Therapies targeting these events have been unsuccessful; findings in experimental models suggest that CD8+ T cells drive disease pathogenesis. However, these data have largely been ignored because corroborating evidence in humans is lacking. This work fills a critical gap in our understanding of CM pathogenesis that is impeding development of therapeutics.METHODSUsing multiplex immunohistochemistry, we characterized cerebrovascular immune cells in brain sections from 34 children who died from CM or other causes. Children were grouped by clinical diagnosis (CM+ or CM-), iRBC sequestration (Seqhi, Seqlo, Seq0) and HIV status (HIV+ or HIV-).RESULTSWe identified effector CD3+CD8+ T cells engaged on the cerebrovasculature in 69% of CM+ HIV- children. The number of intravascular CD3+CD8+ T cells was influenced by CM status (CM+ > CM-, P = 0.004) and sequestration level (Seqhi > Seqlo, P = 0.010). HIV coinfection significantly increased T cell numbers (P = 0.017) and shifted cells from an intravascular (P = 0.004) to perivascular (P < 0.0001) distribution.CONCLUSIONWithin the studied cohort, CM is associated with cerebrovascular engagement of CD3+CD8+ T cells, which is exacerbated by HIV coinfection. Thus, CD3+CD8+ T cells are highly promising targets for CM adjunctive therapy, opening new avenues for the treatment of this deadly disease.FUNDINGThis research was supported by the Intramural Research Program of the National Institutes of Health.

Rates and risk factors for suicidal ideation, suicide attempts and suicide deaths in persons with HIV: a systematic review and meta-analysis

BACKGROUND

People living with HIV/AIDS (PLWHA) must contend with a significant burden of disease. However, current studies of this demographic have yielded wide variations in the incidence of suicidality (defined as suicidal ideation, suicide attempt and suicide deaths).

AIMS

This systematic review and meta-analysis aimed to assess the lifetime incidence and prevalence of suicidality in PLWHA.

METHODS

Publications were identified from PubMed (MEDLINE), SCOPUS, OVID (MEDLINE), Joanna Briggs Institute EBP and Cochrane Library databases (from inception to before 1 February 2020). The search strategy included a combination of Medical Subject Headings associated with suicide and HIV. Researchers independently screened records, extracted outcome measures and assessed study quality. Data were pooled using a random-effects model. Subgroup and meta-regression analyses were conducted to explore the associated risk factors and to identify the sources of heterogeneity. Main outcomes were lifetime incidence of suicide completion and lifetime incidence and prevalence of suicidal ideation and suicide attempt.

RESULTS

A total of 185 199 PLWHA were identified from 40 studies (12 cohorts, 27 cross-sectional and 1 nested case-control). The overall incidence of suicide completion in PLWHA was 10.2/1000 persons (95%CI: 4.5 to 23.1), translating to 100-fold higher suicide deaths than the global general population rate of 0.11/1000 persons. The lifetime prevalence of suicide attempts was 158.3/1000 persons (95%CI: 106.9 to 228.2) and of suicidal ideation was 228.3/1000 persons (95%CI: 150.8 to 330.1). Meta-regression revealed that for every 10-percentage point increase in the proportion of people living with HIV with advanced disease (AIDS), the risk of suicide completion increased by 34 per 1000 persons. The quality of evidence by Grading of Recommendations, Assessment, Development and Evaluations for the suicide deaths was graded as 'moderate' quality.

CONCLUSIONS

The risk of suicide death is 100-fold higher in people living with HIV than in the general population. Lifetime incidence of suicidal ideation and attempts are substantially high. Suicide risk assessments should be a priority in PLWHA, especially for those with more advanced disease.

Mutation of the dyslexia-associated gene Dcdc2 impairs LTM and visuo-spatial performance in mice

Developmental reading disorder (RD) affects 5-10% of school aged children, with a heritability of approximately 60%. Genetic association studies have identified several candidate RD susceptibility genes, including DCDC2; however, a direct connection between the function of these genes and cognitive or learning impairments remains unclear. Variants in DCDC2, a member of the doublecortin family of genes, have been associated in humans with RD and ADHD and Dcdc2 may play a role in neuronal migration in rats. In this study, we examined the effect of Dcdc2 mutation on cognitive abilities in mice using a visual attention and visuo-spatial learning and memory task. We show that both heterozygous and homozygous mutations of Dcdc2 result in persistent visuo-spatial memory deficits, as well as visual discrimination and long-term memory deficits. These behavioral deficits occur in the absence of neuronal migration disruption in the mutant mice, and may be comorbid with an anxiety phenotype. These are the first results to suggest a direct relationship between induced mutation in Dcdc2 and changes in behavioral measures. Dcdc2 mutant mice should prove useful in future studies designed to further dissect the underlying neural mechanisms that are impaired following Dcdc2 mutation.

Leukocyte Isolation from Brain, Spinal Cord, and Meninges for Flow Cytometric Analysis

A continual dialogue exists between the central nervous system (CNS) and immune system that contributes to neural homeostasis as well as protection from microbes, repair following damage, autoimmune disease, and neurodegeneration. Characterization of resident and peripherally derived leukocyte populations within the central nervous system can provide valuable information regarding how these cells contribute to steady-state and inflammatory conditions. Flow cytometry provides a method to conduct detailed multi-parameter analyses of immune cells isolated from various tissues. This protocol provides a method to isolate leukocytes from brain, spinal cord, and meninges for flow cytometric analysis and provides a basic framework for phenotyping these cells. © 2018 by John Wiley & Sons, Inc.

Adenosine A2A Receptor Activation Enhances Blood-Tumor Barrier Permeability in a Rodent Glioma Model

The blood-tumor barrier (BTB) limits the entry of effective chemotherapeutic agents into the brain for treatment of malignant tumors like glioblastoma. Poor drug entry across the BTB allows infiltrative glioma stem cells to evade therapy and develop treatment resistance. Regadenoson, an FDA-approved adenosine A2A receptor (A2AR) agonist, has been shown to increase drug delivery across the blood-brain barrier in non-tumor-bearing rodents without a defined mechanism of enhancing BTB permeability. Here, we characterize the time-dependent impact of regadenoson on brain endothelial cell interactions and paracellular transport, using mouse and rat brain endothelial cells and tumor models. In vitro, A2AR activation leads to disorganization of cytoskeletal actin filaments by 30 minutes, downregulation of junctional protein expression by 4 hours, and reestablishment of endothelial cell integrity by 8 hours. In rats bearing intracranial gliomas, regadenoson treatment results in increase of intratumoral temozolomide concentrations, yet no increased survival noted with combined temozolomide therapy. These findings demonstrate regadenoson's ability to induce brain endothelial structural changes among glioma to increase BTB permeability. The use of vasoactive mediators, like regadenoson, which transiently influences paracellular transport, should further be explored to evaluate their potential to enhance central nervous system treatment delivery to aggressive brain tumors. IMPLICATIONS: This study provides insight on the use of a vasoactive agent to increase exposure of the BTB to chemotherapy with intention to improve glioma treatment efficacy.

Intravital Imaging of Neuroimmune Interactions Through a Thinned Skull

Innate and adaptive immune interactions within the central nervous system (CNS) and surrounding meninges contribute significantly to neural homeostasis as well as a variety of different neurological disorders. Two-photon laser scanning microscopy is a deep tissue imaging technique that provides a means to image immune cell dynamics and interactions in the living CNS with high spatial and temporal resolution. Optical access to the brain and meninges can be achieved through the creation of thinned skull windows, which can be made without inducing damage and inflammation in the underlying tissue. This protocol provides guidance on how to create a thinned skull window without causing CNS injury. We also describe a highly reproducible method to induce a mild traumatic brain injury using the thinned skull approach. © 2018 by John Wiley & Sons, Inc.

Differential seizure response in two models of cortical heterotopia

Malformations of cortical development (MCD) are linked to epilepsy in humans. MCD encompass a broad spectrum of malformations, which occur as the principal pathology or a secondary disruption. Recently, Rosen et al. (2012) reported that BXD29-Trl4(lps-2J)/J mice have subcortical nodular heterotopias with partial agenesis of the corpus callosum (p-ACC). Additionally Ramos et al. (2008) demonstrated that C57BL/10J mice exhibit cortical heterotopias with no additional cortical abnormalities. We examined the seizure susceptibility of these mice to determine if the presence (BXD29-Trl4(lps-2J)/J) or absence (C57BL/10J) of p-ACC, in strains with MCD, confers a differential response to chemi-convulsive treatment. Our results indicate that C57BL/10J mice with layer I heterotopia are more susceptible, whereas BXD29-Trl4(lps-2J)/J mice with more severe subcortical nodular heterotopia and p-ACC are more resistant to seizure behavior induced by pentylenetetrazole. These data suggest that p-ACC may confer seizure resistance in models of MCD.

Method to quantify cytokines and chemokines in mouse brain tissue using Bio-Plex multiplex immunoassays

This protocol describes how to prepare mouse brain tissue for quantification of multiple inflammatory mediators using a multiplex bead-based immunoassay. It is important to have methods that allow quantification of multiple analytes from small amounts of tissue. Bio-Plex is a Luminex xMAP-based multiplex bead-based immunoassay technology that permits simultaneous analysis of up to 100 analytes from a single tissue sample. This assay has been used extensively to investigate analytes in plasma and serum samples as well as cultured and primary cells. Here, we describe a method for simultaneous analysis of 33 different inflammatory cytokines and chemokines from mouse brain tissue using the Bio-Plex Pro Mouse Chemokine Panel 33-Plex.

Anemia in newborn

Various blood indices vary in a newborn as compared to older child or adult. It depends on the gestational age, day of life, maternal factors, mode of delivery and site of blood collection. Hemoglobin, HCT & MCV tend to be higher in newborns. They further increase in first 2 days of life. Reticulocytosis and presence of nucleated red cells are normally seen in first week of life. Neonatal anemia is a common problem in NICU. It is usually caused by either hemorrhage or hemolysis and rarely due to decreased production. Hemorrhage can be ante or intra or post natal and it could be external or internal. It could be acute or chronic. Management of acute severe hemorrhage includes packed cell transfusion. Hemolysis is usually due to isoimmune hemolysis, G6PD deficiency or rarely due to the hemoglobinopathy like alpha-thalassemia or due to spherocytosis. Usually patients will have indirect hyperbilirubinemia which needs phototherapy or exchange transfusion. Rarely congenital pure red cell aplasia can present at birth with physical anomalies and anemia. Treatment of neonatal anemia depends on the arteriology.

Families of Children Newly Diagnosed With Cancer Incur Significant Out-of-Pocket Expenditure for Treatment: Report of a Multi-Site Prospective Longitudinal Study From India (INPOG-ACC-16-01)

Background: Diagnosis of cancer in a child places considerable economic burden on families. The health expenditures are more catastrophic in resource limited countries like India where GDP spend on health is just over 1% and financing of treatment is usually out-of-pocket (OOP). Consequently parents may abandon their child's cancer treatment to ensure financial sustainability of the family. Research in this area is mostly from resource rich countries and OOP expenditure burden remains unknown in India. Aim: The objective of this study is to describe the OOP expenditure incurred by families of children (< 18 years age) with cancer being treated in India prior to and during cancer directed treatment. Methods: A prospective cost of illness study from a family household perspective was conducted in 14 centers (5 public, 5 private and 4 charitable trust sector) in 4 cities in India from 2016-2018. Baseline family demographic and socioeconomic data were collected followed by OOP expenditure incurred prior to start of treatment. For the duration of the child's treatment, a social worker contacted parents at regular intervals to record their expenditure on cancer directed treatment. Data collection was stopped when one of these happened - completion of treatment or death or progression/relapse or abandonment or transfer. Data were described descriptively and a univariate/multivariate analysis using logistic regression was done to detect factors associated with OOP expenditure. Results: 394 children (63% male, median age 5 years) with cancer (64% leukemia/lymphoma, 33% solid tumors, 3% CNS tumors) were enrolled from public (45%), charitable trust (28%) and private (27%) sector hospitals. They were symptomatic for a median duration of 6 weeks (range 0 to 104 weeks). 88% had no insurance and 73% were from families with monthly income of ≤ 10,000 rupees (≤ 159 US$). Mean OOP expenditure was Rs 209,500 (3325 US$) which is 195% of per capita income (1706 US$) of India. OOP expenditure from onset of symptoms to start of treatment was Rs 53,104 (843 US$) of which 77% was medical (15% laboratory tests, 11% medicines, 9% hospital bed costs) and 23% nonmedical (12% travel, 6% food, 3% lodging). OOP expenditure on cancer directed treatment was Rs 156,396 (2482 US$) of which 64% was medical (9% hospital bed costs, 9% supportive care drugs, 8% laboratory tests) and 36% nonmedical (19% food, 9% travel, 6% lodging). On univariate analysis age, gender, city, type of treatment facility, insurance, type of cancer, driving time and distance were significantly associated with OOP expenditure but only insurance and type of treatment facility were found significant on multivariate analysis. Conclusion: Families of children with cancer incur significant OOP expenditure prior to and during cancer directed treatment, which includes a significant portion on nonmedical expenses. Expenditure varied significantly by insurance and type of treatment facility.

Translating dyslexia across species

Direct relationships between induced mutation in the DCDC2 candidate dyslexia susceptibility gene in mice and changes in behavioral measures of visual spatial learning have been reported. We were interested in determining whether performance on a visual-spatial learning and memory task could be translated across species (study 1) and whether children with reading impairment showed a similar impairment to animal models of the disorder (study 2). Study 1 included 37 participants who completed six trials of four different virtual Hebb-Williams maze configurations. A 2 × 4 × 6 mixed factorial repeated measures ANOVA indicated consistency in performance between humans and mice on these tasks, enabling us to translate across species. Study 2 included a total of 91 participants (age range = 8-13 years). Eighteen participants were identified with reading disorder by performance on the Woodcock-Johnson III Tests of Achievement. Participants completed six trials of five separate virtual Hebb-Williams maze configurations. A 2 × 5 × 6 mixed factorial ANCOVA (gender as covariate) indicated that individuals with reading impairment demonstrated impaired visuo-spatial performance on this task. Overall, results from this study suggest that we are able to translate behavioral deficits observed in genetic animal models of dyslexia to humans with reading impairment. Future studies will utilize the virtual environment to further explore the underlying basis for this impairment.

Anti-NMDAR Encephalitis After Neonatal HSV-1 Infection in a Child With Low TLR-3 Function

Neonatal herpes simplex virus encephalitis (HSVE) often results in long-lasting neuro-disability in affected children. In addition to primary HSVE and HSVE relapses, children with herpes simplex virus are at increased risk of developing anti-N-methyl-d-aspartate receptor encephalitis (NMDARe), an autoimmune encephalitis. In this study, we describe a patient with neonatal disseminated herpes infection, who developed HSVE after discontinuation of 2 years of acyclovir suppressive therapy. After resolution of HSVE, the patient rapidly deteriorated with significant behavioral and neurologic changes including emotional outbursts, fearfulness, involuntary movements, and focal seizures. The patient was diagnosed with anti-NMDARe and was later found to have low toll-like receptor-3 function. In this study, we review published pediatric cases of anti-NMDARe after HSVE as well as previous literature and primary data examining the presentation, predisposing risk factors, predictive outcomes, future directions, and the role of immunodeficiency in HSVE-mediated anti-NMDARe. The neonatal immune system and developing brain are disproportionately vulnerable to early viral exposure; therefore, it is important to recognize the value of early immunodeficiency screening in patients with neonatal herpes simplex virus. By understanding the immune landscape within this patient population, we can mitigate long-term neurologic disability and improve the quality of life of affected children.

Dichotomous regulation of progenitor-like CD8 T cells during chronic viral infection by TCF1 and type I interferon

T cells develop into a dysfunctional state, called T-cell exhaustion, during chronic viral infections and cancer. However, how antigen-specific T cells persist in these situations is poorly understood. Here, we show that CD8 T cells differentiate into a less exhausted TCF1highTim3low subset and a more exhausted TCF1lowTim3high subset in chronic viral infection as well as human and mouse solid tumors. The TCF1highTim3low CD8 T cells, generated early after chronic lymphocytic choriomeningitis virus (LCMV) infection, persist better and mount a far stronger secondary response than TCF1lowTim3high cells. Importantly, TCF1highTim3low cells act as progenitor cells that are capable of both self-renewal and terminally differentiating into TCF1lowTim3high cells. We have further shown that cell-intrinsic TCF1 signaling is necessary and sufficient to program these progenitors early after infection. Cell-intrinsic TCF1 deficiency led to a progressive loss of anti-viral CD4 and CD8 T cell responses during the chronic phase of infection. Several pro-exhaustion factors, including Tim3, Cish, and Blimp1, are suppressed by TCF1. Conversely, TCF1 up-regulates Bcl6, which strongly enforces the progenitor fate. Moreover, cell-intrinsic type I interferon signal suppresses the differentiation of progenitor-like CD8 T cells, and antibody-mediated blockade of IFNAR1 enhances the differentiation of these CD8 T cells in a TCF1-dependent manner. Thus, our study not only identifies a CD8 progenitor population, which is critical for long-term persistence of anti-viral CD8 responses during chronic viral infection, but also uncovers both positive and negative regulators of the early programming of this population.

'NESTROFT'--an effective screening test for beta thalassemia trait

OBJECTIVE

To evaluate the efficacy of NESTROFT (Naked Eye Single Tube Red Cell Osmotic Fragility Test) as a screening tool for detection of beta thalassemia trait.

DESIGN

Prospective study.

SETTING

Field camps in various parts of Gujarat and Maharashtra States.

METHODS

A total of 2525 subjects were screened. NESTROFT, complete hemogram including red cell indices and calculation of Mentzer's Fraction (MF) and discriminant functions (DF1-4) were done in all subjects. HbA2 was performed in 830 initial subjects to compute sensitivity, specificity and predictive values for various parameters.

RESULTS

NESTROFT (sensitivity 94.4%), as a single screening parameter was superior to any of the other evaluated parameters individually, besides being cost effective. Mean corpuscular volume (MCV) < 80 fl followed NESTROFT closely (sensitivity 93.7; p > 0.05). MCV < 75 fl had a significantly (p < 0.001) lower sensitivity (87.3%) in comparison to both of these parameters. In contrast, MF, DF1, DF2, DF3 and DF4 did not meet the requirements of a good screening test with sensitivity values of 66.2%, 54.9%, 47.2%, 64.1% and 55.6%, respectively. NESTROFT in combination with MCV < 80 fl proved 100% sensitive. However, the combination was not cost effective.

CONCLUSION

NESTROFT is a sensitive, cost effective, rapid and reliable screening test for detection of beta thalassemia trait in a population.

Peptide-Specific Engagement of Cerebrovascular Endothelial Cells Promotes Dysfunctional Calcium Signaling During Experimental Cerebral Malaria

Cerebral malaria is a potentially fatal complication associated with Plasmodium falciparum infection. Disease pathology includes blood brain barrier (BBB) breakdown, microvascular hemorrhage, edema and brainstem herniation. Studies in rodents (referred to as experimental cerebral malaria) have revealed that parasite-specific CD8+ T cells induce this pathology via engagement of cerebrovascular endothelial cells (ECs). In this study, we sought novel insights into the mechanisms underlying alterations in BBB structure and function during the development of ECM. We developed a novel transgenic reporter system that allowed us to simultaneously monitor calcium signaling in cerebrovascular ECs and parasite-specific CD8+ T cells. We then used intravital two-photon microscopy (TPM) to monitor BBB dynamics in real-time at the peak of disease. Within venous networks, we observed a significant increase in the magnitude and propagation of EC calcium signaling. Calcium wave propagation along lengthy stretches of cerebrovascular endothelium was associated with regions of parasite-specific CD8+ T cell engagement (both stable and dynamic). Recognition of cognate peptide-MHC on luminal and abluminal EC surfaces resulted in calcium fluxes within parasite-specific CD8+ T cells, which was followed temporally by calcium wave propagation in the associated vasculature. Importantly, this pathophysiological response was completely eliminated by depletion of T cells. We postulate that T cell-mediated induction of calcium waves along cerebral blood vessels promotes noncytopathic disruption of the BBB. Therapeutic manipulation of this activity might help restore BBB homeostasis and prevent neurological complications during ECM.

Clinical spectrum of HIV infection

OBJECTIVE

To study the modes of transmission of pediatric HIV infection, to categorize clinical manifestations and to compare clinical spectrum of perinatal with transfusion acquired HIV infection.

DESIGN

Case series study.

SETTING

Hospital based pediatric HIV clinic.

METHODS

Children confirmed to have HIV infection were evaluated and relevant details recorded.

RESULTS

55 children were enrolled of whom 41 (74.5%) had perinatal transmission of HIV, 12 (21.8%) were infected through blood transfusions and 2 (3.6%) through other routes. Thirty-seven (90.2%) of the 41 perinatally infected children were symptomatic. Tuberculosis was seen in 25 (67.5%) of these children and failure to thrive in 18 (48.6%). Nonspecific features such as recurrent bacterial infection, oral candidiasis and chronic diarrhea were other manifestations. Eight (26.3%) of the 30 children available for follow up for a median period of 9 months died at the median age of 8.5 months. Amongst the transfusion acquired HIV infection, 11 (91.6%) of the 12 were asymptomatic at presentation. Six (50%) of these children died at the median age of 3 years and the remaining 6 had no major symptoms at a median follow up of 3.5 years.

CONCLUSION

Perinatal route is the major route of HIV transmission in children and clinical manifestations are different from those of adults.