Role of SHIP1 in Invariant NKT Cell Development and Functions.

SHIP1 is a 5'-inositol phosphatase known to negatively regulate the signaling product of the PI3K pathway, phosphatidylinositol (3-5)-trisphosphate. SHIP1 is recruited to a large number of inhibitory receptors expressed on invariant NK (iNKT) cells. We hypothesized that SHIP1 deletion would have major effects on iNKT cell development by altering the thresholds for positive and negative selection. Germline SHIP1 deletion has been shown to affect T cells as well as other immune cell populations. However, the role of SHIP1 on T cell function has been controversial, and its participation on iNKT cell development and function has not been examined. We evaluated the consequences of SHIP1 deletion on iNKT cells using germline-deficient mice, chimeric mice, and conditionally deficient mice. We found that T cell and iNKT cell development are impaired in germline-deficient animals. However, this phenotype can be rescued by extrinsic expression of SHIP1. In contrast, SHIP1 is required cell autonomously for optimal iNKT cell cytokine secretion. This suggests that SHIP1 calibrates the threshold of iNKT cell reactivity. These data further our understanding of how iNKT cell activation is regulated and provide insights into the biology of this unique cell lineage.

Non-alcoholic fatty liver disease induces signs of Alzheimer's disease (AD) in wild-type mice and accelerates pathological signs of AD in an AD model.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease afflicting about one third of the world's population and 30 % of the US population. It is induced by consumption of high-lipid diets and is characterized by liver inflammation and subsequent liver pathology. Obesity and consumption of a high-fat diet are known to increase the risk of Alzheimer's disease (AD). Here, we investigated NAFLD-induced liver inflammation in the pathogenesis of AD. METHODS: WT and APP-Tg mice were fed with a standard diet (SD) or a high-fat diet (HFD) for 2, 5 months, or 1 year to induce NAFLD. Another set of APP-Tg mice were removed from HFD after 2 months and put back on SD for 3 months. RESULTS: During acute phase NAFLD, WT and APP-Tg mice developed significant liver inflammation and pathology that coincided with increased numbers of activated microglial cells in the brain, increased inflammatory cytokine profile, and increased expression of toll-like receptors. Chronic NAFLD induced advanced pathological signs of AD in both WT and APP-Tg mice, and also induced neuronal apoptosis. We observed decreased brain expression of low-density lipoprotein receptor-related protein-1 (LRP-1) which is involved in ß-amyloid clearance, in both WT and APP-Tg mice after ongoing administration of the HFD. LRP-1 expression correlated with advanced signs of AD over the course of chronic NAFLD. Removal of mice from HFD during acute NAFLD reversed liver pathology, decreased signs of activated microglial cells and neuro-inflammation, and decreased ß-amyloid plaque load. CONCLUSIONS: Our findings indicate that chronic inflammation induced outside the brain is sufficient to induce neurodegeneration in the absence of genetic predisposition.

CD73-generated adenosine is critical for immune regulation during Toxoplasma gondii infection.

As an obligate intracellular pathogen, the apicomplexan parasite Toxoplasma gondii evades immune system-mediated clearance by undergoing stage differentiation to persist indefinitely in susceptible hosts. Previously, we found that mice deficient in the ectoenzyme CD73, which generates adenosine in the extracellular matrix, were resistant to chronic toxoplasmosis after oral infection with T. gondii. Resistance in CD73 knockout mice was due to a delay in parasite differentiation in the central nervous system (CNS). To further clarify the role of CD73 and extracellular adenosine in T. gondii pathogenesis, we infected wild-type (WT) and CD73(-/-) mice with T. gondii cysts systemically by the intraperitoneal (i.p.) route. In contrast to oral infection, i.p. infected CD73(-/-) mice were highly susceptible to immune-mediated pathology, with significantly increased infiltration of neutrophils and T cells into the peritoneal cavity. Administration of the broad-spectrum adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) protected CD73(-/-) mice against T. gondii-induced immunopathology, suggesting that the absence of CD73-generated adenosine led to the increased susceptibility in these mice. Peritoneal exudate cells from infected CD73(-/-) mice produced higher levels of the inflammatory mediators nitric oxide, tumor necrosis factor alpha (TNF-α), and interleukin-1ß (IL-1ß), without enhanced parasite killing or clearance. Bone marrow chimeras established that CD73 expression in both hematopoietic and nonhematopoietic compartments contributes to limiting T. gondii-induced immunopathology. In addition, mice deficient in the adenosine receptor A(2A) were more susceptible to immunopathology during intraperitoneal infection with T. gondii than WT mice. Thus, extracellular adenosine is a key immune regulator that limits collateral tissue damage due to an intracellular pathogen and promotes host survival.

Safety and immunogenicity of a thermostable ID93 + GLA-SE tuberculosis vaccine candidate in healthy adults.

Adjuvant-containing subunit vaccines represent a promising approach for protection against tuberculosis (TB), but current candidates require refrigerated storage. Here we present results from a randomized, double-blinded Phase 1 clinical trial (NCT03722472) evaluating the safety, tolerability, and immunogenicity of a thermostable lyophilized single-vial presentation of the ID93 + GLA-SE vaccine candidate compared to the non-thermostable two-vial vaccine presentation in healthy adults. Participants were monitored for primary, secondary, and exploratory endpoints following intramuscular administration of two vaccine doses 56 days apart. Primary endpoints included local and systemic reactogenicity and adverse events. Secondary endpoints included antigen-specific antibody (IgG) and cellular immune responses (cytokine-producing peripheral blood mononuclear cells and T cells). Both vaccine presentations are safe and well tolerated and elicit robust antigen-specific serum antibody and Th1-type cellular immune responses. Compared to the non-thermostable presentation, the thermostable vaccine formulation generates greater serum antibody responses (p < 0.05) and more antibody-secreting cells (p < 0.05). In this work, we show the thermostable ID93 + GLA-SE vaccine candidate is safe and immunogenic in healthy adults.

Chromosome y regulates survival following murine coxsackievirus b3 infection.

Coxsackievirus B3 (CVB3) contributes to the development of myocarditis, an inflammatory heart disease that predominates in males, and infection is a cause of unexpected death in young individuals. Although gonadal hormones contribute significantly to sex differences, sex chromosomes may also influence disease. Increasing evidence indicates that Chromosome Y (ChrY) genetic variants can impact biological functions unrelated to sexual differentiation. Using C57BL/6J (B6)-ChrY consomic mice, we show that genetic variation in ChrY has a direct effect on the survival of CVB3-infected animals. This effect is not due to potential Sry-mediated differences in prenatal testosterone exposure or to differences in adult testosterone levels. Furthermore, we show that ChrY polymorphism influences the percentage of natural killer T cells in B6-ChrY consomic strains but does not underlie CVB3-induced mortality. These data underscore the importance of investigating not only the hormonal regulation but also ChrY genetic regulation of cardiovascular disease and other male-dominant, sexually dimorphic diseases and phenotypes.