Differential Integrin Adhesome Expression Defines Human NK Cell Residency and Developmental Stage.

NK cells are innate immune cells that reside within tissue and circulate in peripheral blood. They interact with a variety of microenvironments, yet how NK cells engage with these varied microenvironments is not well documented. The adhesome represents a molecular network of defined and predicted integrin-mediated signaling interactions. In this study, we define the integrin adhesome expression profile of NK cells from human tonsil, peripheral blood, and those derived from human hematopoietic precursors through stromal cell coculture systems. We report that the site of cell isolation and NK cell developmental stage dictate differences in expression of adhesome associated genes and proteins. Furthermore, we define differences in cortical actin content associated with differential expression of actin regulating proteins, suggesting that differences in adhesome expression are associated with differences in cortical actin homeostasis. These data provide understanding of the diversity of human NK cell populations and how they engage with their microenvironment.

Longitudinal profiling of respiratory and systemic immune responses reveals myeloid cell-driven lung inflammation in severe COVID-19.

Immune response dynamics in coronavirus disease 2019 (COVID-19) and their severe manifestations have largely been studied in circulation. Here, we examined the relationship between immune processes in the respiratory tract and circulation through longitudinal phenotypic, transcriptomic, and cytokine profiling of paired airway and blood samples from patients with severe COVID-19 relative to heathy controls. In COVID-19 airways, T cells exhibited activated, tissue-resident, and protective profiles; higher T cell frequencies correlated with survival and younger age. Myeloid cells in COVID-19 airways featured hyperinflammatory signatures, and higher frequencies of these cells correlated with mortality and older age. In COVID-19 blood, aberrant CD163+ monocytes predominated over conventional monocytes, and were found in corresponding airway samples and in damaged alveoli. High levels of myeloid chemoattractants in airways suggest recruitment of these cells through a CCL2-CCR2 chemokine axis. Our findings provide insights into immune processes driving COVID-19 lung pathology with therapeutic implications for targeting inflammation in the respiratory tract.

Case Report: Secondary Hemophagocytic Lymphohistiocytosis With Disseminated Infection in Chronic Granulomatous Disease-A Serious Cause of Mortality.

Chronic granulomatous disease (CGD) is a primary immune deficiency due to defects in phagocyte respiratory burst leading to severe and life-threatening infections. Patients with CGD also suffer from disorders of inflammation and immune dysregulation including colitis and granulomatous lung disease, among others. Additionally, patients with CGD may be at increased risk of systemic inflammatory disorders such as hemophagocytic lymphohistiocytosis (HLH). The presentation of HLH often overlaps with symptoms of systemic inflammatory response syndrome (SIRS) or sepsis and therefore can be difficult to identify, especially in patients with a primary immune deficiency in which incidence of infection is increased. Thorough evaluation and empiric treatment for bacterial and fungal infections is necessary as HLH in CGD is almost always secondary to infection. Simultaneous treatment of infection with anti-microbials and inflammation with immunosuppression may be needed to blunt the hyperinflammatory response in secondary HLH. Herein, we present a series of X-linked CGD patients who developed HLH secondary to or with concurrent disseminated CGD-related infection. In two patients, CGD was a known diagnosis prior to development of HLH and in the other two CGD was diagnosed as part of the evaluation for HLH. Concurrent infection and HLH were fatal in three; one case was successfully treated, ultimately receiving hematopoietic stem cell transplantation. The current literature on presentation, diagnosis, and treatment of HLH in CGD is reviewed.

Impact and Clinical Implications of Prematurity on Adaptive Immune Development.

PURPOSE OF REVIEW: Detail normal adaptive immune maturation during fetal and neonatal life and review the clinical implications of arrested immune development. RECENT FINDINGS: Advancements in the field of immunology have enabled investigations of the adaptive immunity starting during fetal life. New insights have drawn important distinctions between the neonatal and adult immune systems. The presence of diverse immunologic responses in the perinatal period suggests the importance of in utero immune development. Disruption of immune maturation due to premature birth may have significant implications for clinical pathology. SUMMARY: Establishing protective adaptive immunity during the perinatal period is critical for effective immune responses later in life. Preterm infants are susceptible to aberrant immune system maturation and inflammatory immune responses have been associated with the development of necrotizing enterocolitis (NEC) and bronchopulmonary dysplasia (BPD). Improving our understanding of how immune responses contribute to the pathogenesis of NEC and BPD may offer new opportunities for future treatment and prevention of these diseases.

Human T Cell Development, Localization, and Function throughout Life.

Throughout life, T cells coordinate multiple aspects of adaptive immunity, including responses to pathogens, allergens, and tumors. In mouse models, the role of T cells is studied in the context of a specific type of pathogen, antigen, or disease condition over a limited time frame, whereas in humans, T cells control multiple insults simultaneously throughout the body and maintain immune homeostasis over decades. In this review, we discuss how human T cells develop and provide essential immune protection at different life stages and highlight tissue localization and subset delineation as key determinants of the T cell functional role in immune responses. We also discuss how anatomic compartments undergo distinct age-associated changes in T cell subset composition and function over a lifetime. It is important to consider age and tissue influences on human T cells when developing targeted strategies to modulate T cell-mediated immunity in vaccines and immunotherapies.

Airway CD8(+) T Cells Are Associated with Lung Injury during Infant Viral Respiratory Tract Infection.

Infants and young children are disproportionately susceptible to severe complications from respiratory viruses, although the underlying mechanisms remain unknown. Recent studies show that the T cell response in the lung is important for protective responses to respiratory infections, although details on the infant/pediatric respiratory immune response remain sparse. The objectives of the present study were to characterize the local versus systemic immune response in infants and young children with respiratory failure from viral respiratory tract infections and its association to disease severity. Daily airway secretions were sampled from infants and children 4 years of age and younger receiving mechanical ventilation owing to respiratory failure from viral infection or noninfectious causes. Samples were examined for immune cell composition and markers of T cell activation. These parameters were then correlated with clinical disease severity. Innate immune cells and total CD3(+) T cells were present in similar proportions in airway aspirates derived from infected and uninfected groups; however, the CD8:CD4 T cell ratio was markedly increased in the airways of patients with viral infection compared with uninfected patients, and specifically in infected infants with acute lung injury. T cells in the airways were phenotypically and functionally distinct from those in blood with activated/memory phenotypes and increased cytotoxic capacity. We identified a significant increase in airway cytotoxic CD8(+) T cells in infants with lung injury from viral respiratory tract infection that was distinct from the T cell profile in circulation and associated with increasing disease severity. Airway sampling could therefore be diagnostically informative for assessing immune responses and lung damage.

The phosphatidylinositol 3-kinase inhibitor LY 294002 inhibits GlyT1-mediated glycine uptake.

The actions of neurotransmitter glycine are regulated by the Na+/Cl(-) dependent high-affinity glycine transporters, GlyT1 and GlyT2. These two members of the SLC6 transport family have been cloned and extensively characterized, however relatively little is known regarding their modulation. In the present study, glycine uptake in primary cultures of rat embryonic cortex has been characterized and the effects of the phosphatidylinositol 3 (PI3) kinase inhibitors LY 294002 and wortmannin on GlyT1- and GlyT2-mediated glycine uptake were investigated. GlyT1 inhibitors ALX 5407 and sarcosine reduced total glycine uptake to 80% whereas the specific GlyT2 inhibitor Org 25543 had no effect. In the presence of alanine, glycine uptake was completely blocked by the GlyT1 inhibitors ALX 5407 and sarcosine, suggesting that the high-affinity glycine uptake occurs predominantly via GlyT1. Kinetic analysis of GlyT1 revealed the Km value of 27+/-1.5 microM and Vmax value of 157+/-14 pmol/mg/min. LY 294002, a PI3 kinase inhibitor, blocked the GlyT1-mediated glycine uptake with an IC50 value of 81+/-2 microM, whereas another inhibitor wortmannin did not show any effect. In human placental choriocarcinoma (JAR) cells, which have been previously shown to predominantly express GlyT1a, LY 294002 showed a similar potency with an IC50 value of 86+/-3 microM. Immunoblots demonstrated that LY 294002 and wortmannin inhibited PI3 kinase-dependent Akt phosphorylation in the primary cultures with IC50 values of 10+/-4 microM and 7+/-1 nM, respectively. These results suggest that the commonly used PI3 kinase blocker LY 294002 may modulate GlyT1 function independent of PI3 kinase inhibition. Kinetic analysis in the presence of LY 294002 demonstrated significant decreases of both Km and Vmax values, suggesting a mechanism of uncompetitive inhibition on GlyT1-mediated glycine uptake. In addition, glycine release was blocked by LY 294002. These results raised a possibility that LY 294002 might interact with GlyT1.