Conditional ablation of NKp46+ cells using a novel Ncr1greenCre mouse strain: NK cells are essential for protection against pulmonary B16 metastases

To study gene functions specifically in NKp46⁺ cells we developed novel Cre mice allowing for conditional gene targeting in cells expressing Ncr1 (encoding NKp46). We generated transgenic Ncr1^greenCre mice carrying an EGFPcre fusion under the control of a proximal Ncr1 promoter that faithfully directed EGFPcre expression to NKp46⁺ cells from lymphoid and nonlymphoid tissues. This approach allowed for direct detection of Cre‐expressing NKp46⁺ cells via their GFP signature by flow cytometry and histology. Cre was functional as evidenced by the NKp46⁺ cell‐specific expression of RFP in Ncr1^greenCreRosa‐dtRFP reporter mice. We generated Ncr1^greenCreIl2rg^fl/fl mice that lack NKp46⁺ cells in an otherwise intact hematopoietic environment. Il2rg encodes the common gamma chain (γ_c), which is an essential receptor subunit for cytokines (IL‐2, ‐4, ‐7, ‐9, ‐15, and ‐21) that stimulate lymphocyte development and function. In Ncr1^greenCreIl2rg^fl/fl mice, NK cells are severely reduced and the few remaining NKp46⁺ cells escaping γc deletion failed to express GFP. Using this new NK‐cell‐deficient model, we demonstrate that the homeostasis of NKp46⁺ cells from all tissues (including the recently described intraepithelial ILC1 subset) requires Il2rg. Finally, Ncr1^greenCreIl2rg^fl/fl mice are unable to reject B16 lung metastases demonstrating the essential role of NKp46⁺ cells in antimelanoma immune responses.     

Human regulatory T cells lack the cyclophosphamide‐extruding transporter ABCB1 and are more susceptible to cyclophosphamide‐induced apoptosis

ATP‐binding cassette (ABC) transporters, including ABC‐transporter B1 (ABCB1), extrude drugs, metabolites, and other compounds (such as mitotracker green (MTG)) from cells. Susceptibility of CD4⁺ regulatory T (Treg) cells to the ABCB1‐substrate cyclophosphamide (CPA) has been reported. Here, we characterized ABCB1 expression and function in human CD4⁺ T‐cell subsets. Naïve, central memory, and effector‐memory CD4⁺ T cells, but not Treg cells, effluxed MTG in an ABCB1‐dependent manner. In line with this, ABCB1 mRNA and protein was expressed by nonregulatory CD4⁺ T‐cell subsets, but not Treg cells. In vitro, the ABCB1‐substrate CPA was cytotoxic for Treg cells at a 100‐fold lower dose than for nonregulatory counterparts, and, inversely, verapamil, an inhibitor of ABC transporters, increased CPA‐toxicity in nonregulatory CD4⁺ T cells but not Treg cells. Thus, Treg cells lack expression of ABCB1, rendering them selectively susceptible to CPA. Our findings provide mechanistic support for therapeutic strategies using CPA to boost anti‐tumor immunity by selectively depleting Treg cells.     

Examination of Genetic Variation in GABRA2 with Conduct Disorder and Alcohol Abuse and Dependence in a Longitudinal Study

Previous studies have shown associations between single nucleotide polymorphisms (SNPs) in gamma aminobutyric acid receptor alpha 2 (GABRA2) and adolescent conduct disorder (CD) and alcohol dependence in adulthood, but not adolescent alcohol dependence. The present study was intended as a replication and extension of this work, focusing on adolescent CD, adolescent alcohol abuse and dependence (AAD), and adult AAD. Family based association tests were run using Hispanics and non-Hispanic European American subjects from two independent longitudinal samples. Although the analysis provided nominal support for an association with rs9291283 and AAD in adulthood and CD in adolescence, the current study failed to replicate previous associations between two well replicated GABRA2 SNPs and CD and alcohol dependence. Overall, these results emphasize the utility of including an independent replication sample in the study design, so that the results from an individual sample can be weighted in the context of its reproducibility.     

Estimating the Sex-Specific Effects of Genes on Facial Attractiveness and Sexual Dimorphism

Human facial attractiveness and facial sexual dimorphism (masculinity–femininity) are important facets of mate choice and are hypothesized to honestly advertise genetic quality. However, it is unclear whether genes influencing facial attractiveness and masculinity–femininity have similar, opposing, or independent effects across sex, and the heritability of these phenotypes is poorly characterized. To investigate these issues, we assessed facial attractiveness and facial masculinity–femininity in the largest genetically informative sample (n = 1,580 same- and opposite-sex twin pairs and siblings) to assess these questions to date. The heritability was ~0.50–0.70 for attractiveness and ~0.40–0.50 for facial masculinity–femininity, indicating that, despite ostensible selection on genes influencing these traits, substantial genetic variation persists in both. Importantly, we found evidence for intralocus sexual conflict, whereby alleles that increase masculinity in males have the same effect in females. Additionally, genetic influences on attractiveness were shared across the sexes, suggesting that attractive fathers tend to have attractive daughters and attractive mothers tend to have attractive sons.     

Interleukin-3-Deficient Mice Have Increased Resistance to Blood-Stage Malaria

The contribution of interleukin-3 (IL-3), a hematopoietic growth factor and immunoregulatory cytokine, to resistance to blood-stage malaria was investigated by infecting IL-3-deficient (knockout [KO]) mice with Plasmodium berghei NK65. Male IL-3 KO mice, but not female mice, were more resistant to infection than wild-type (WT) mice, as evidenced by lower peak parasitemia and prolonged survival. Both male and female IL-3 KO mice had increased splenomegaly and were more anemic than corresponding WT mice. Anemia was compensated for by an increase in bone marrow and splenic erythropoiesis in IL-3 KO mice, as evidenced by higher levels of erythroid progenitors. Plasma levels of gamma interferon (IFN-γ) and CXCL9 (monokine induced by IFN-γ [MIG]) were found to be significantly reduced in IL-3 KO mice during early stages of infection. In contrast, granulocyte colony-stimulating factor (G-CSF) levels were significantly higher, and the percentage of peripheral blood neutrophils lower, in infected IL-3 KO mice than in WT counterparts. Overall, our results indicate that IL-3 plays a critical role in suppressing protective immunity to P. berghei NK65 infection and that it is involved in inhibiting the development of splenomegaly, anemia, and erythropoiesis. IL-3 also influences IFN-γ, CXCL9, and G-CSF production in response to infection. The abnormal responses seen in infected IL-3 KO mice may be due to the lack of IL-3 during development, to the lack of IL-3 in the infected mature mice, or to both.     

Thorax Injury Lowers Resistance to Infection in Drosophila melanogaster

The route of infection can profoundly affect both the progression and outcome of disease. We investigated differences in Drosophila melanogaster defense against infection after bacterial inoculation into two sites—the abdomen and the thorax. Thorax inoculation results in increased bacterial proliferation and causes high mortality within the first few days of infection. In contrast, abdomen inoculation results in minimal mortality and lower bacterial loads than thorax inoculation. Inoculation into either site causes systemic infection. Differences in mortality and bacterial load are due to injury of the thorax and can be recapitulated by abdominal inoculation coupled with aseptic wounding of the thorax. This altered resistance appears to be independent of classical immune pathways and opens new avenues of research on the role of injury during defense against infection.