Eomesodermin spatiotemporally orchestrates the early and late stages of NK cell development by targeting KLF2 and T-bet, respectively.

Eomesodermin (Eomes) is a critical factor in the development of natural killer (NK) cells, but its precise role in temporal and spatial coordination during this process remains unclear. Our study revealed that Eomes plays distinct roles during the early and late stages of NK cell development. Specifically, the early deletion of Eomes via the CD122-Cre transgene resulted in significant blockade at the progenitor stage due to the downregulation of KLF2, another important transcription factor. ChIP-seq revealed direct binding of Eomes to the conserved noncoding sequence (CNS) of Klf2. Utilizing the CHimeric IMmune Editing (CHIME) technique, we found that deletion of the CNS region of Klf2 via CRISPRi led to a reduction in the NK cell population and developmental arrest. Moreover, constitutive activation of this specific CNS region through CRISPRa significantly reversed the severe defects in NK cell development caused by Eomes deficiency. Conversely, Ncr1-Cre-mediated terminal deletion of Eomes expedited the transition of NK cell subsets from the CD27+CD11b+ phenotype to the CD27-CD11b+ phenotype. Late-stage deficiency of Eomes led to a significant increase in T-bet expression, which subsequently increased the expression of the transcription factor Zeb2. Genetic deletion of one allele of Tbx21, encoding T-bet, effectively reversed the aberrant differentiation of Eomes-deficient NK cells. In summary, we utilized two innovative genetic models to elucidate the intricate mechanisms underlying Eomes-mediated NK cell commitment and differentiation.

Blocking OLFM4/galectin-3 axis in placental polymorphonuclear myeloid-derived suppressor cells triggers intestinal inflammation in newborns.

Fetal growth restriction (FGR) is a major cause of premature and low-weight births, which increases the risk of necrotizing enterocolitis (NEC); however, the association remains unclear. We report a close correlation between placental polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and NEC. Newborns with previous FGR exhibited intestinal inflammation and more severe NEC symptoms than healthy newborns. Placental PMN-MDSCs are vital regulators of fetal development and neonatal gut inflammation. Placental single-cell transcriptomics revealed that PMN-MDSCs populations and olfactomedin-4 gene (Olfm4) expression levels were significantly increased in PMN-MDSCs in later pregnancy compared to those in early pregnancy and non-pregnant females. Female mice lacking Olfm4 in myeloid cells mated with wild-type males showed FGR during pregnancy, with a decreased placental PMN-MDSCs population and expression of growth-promoting factors (GPFs) from placental PMN-MDSCs. Galectin-3 (Gal-3) stimulated the OLFM4-mediated secretion of GPFs by placental PMN-MDSCs. Moreover, GPF regulation via OLFM4 in placental PMN-MDSCs was mediated via hypoxia inducible factor-1α (HIF-1α). Notably, the offspring of mothers lacking Olfm4 exhibited intestinal inflammation and were susceptible to NEC. Additionally, OLFM4 expression decreased in placental PMN-MDSCs from pregnancies with FGR and was negatively correlated with neonatal morbidity. These results revealed that placental PMN-MDSCs contributed to fetal development and ameliorate newborn intestinal inflammation.

Lkb1 orchestrates γδ T-cell metabolic and functional fitness to control IL-17-mediated autoimmune hepatitis.

γδ T cells play a crucial role in immune surveillance and serve as a bridge between innate and adaptive immunity. However, the metabolic requirements and regulation of γδ T-cell development and function remain poorly understood. In this study, we investigated the role of liver kinase B1 (Lkb1), a serine/threonine kinase that links cellular metabolism with cell growth and proliferation, in γδ T-cell biology. Our findings demonstrate that Lkb1 is not only involved in regulating γδ T lineage commitment but also plays a critical role in γδ T-cell effector function. Specifically, T-cell-specific deletion of Lkb1 resulted in impaired thymocyte development and distinct alterations in γδ T-cell subsets in both the thymus and peripheral lymphoid tissues. Notably, loss of Lkb1 inhibited the commitment of Vγ1 and Vγ4 γδ T cells, promoted the maturation of IL-17-producing Vγ6 γδ T cells, and led to the occurrence of fatal autoimmune hepatitis (AIH). Notably, clearance of γδ T cells or blockade of IL-17 significantly attenuated AIH. Mechanistically, Lkb1 deficiency disrupted metabolic homeostasis and AMPK activity, accompanied by increased mTORC1 activation, thereby causing overactivation of γδ T cells and enhanced apoptosis. Interestingly, activation of AMPK or suppression of mTORC1 signaling effectively inhibited IL-17 levels and attenuated AIH in Lkb1-deficient mice. Our findings highlight the pivotal role of Lkb1 in maintaining the homeostasis of γδ T cells and preventing IL-17-mediated autoimmune diseases, providing new insights into the metabolic programs governing the subset determination and functional differentiation of thymic γδ T cells.

The suppression of sepsis-induced kidney injury via the knockout of T lymphocytes.

Patients with sepsis always have a high mortality rate, and acute kidney injury (AKI) is the main cause of death. It seems obvious that the immune response is involved in this process, but the specific mechanism is unknown, especially the pathogenic role of T cells and B cells needs to be further clarified. Acute kidney injury models induced by lipopolysaccharide were established using T-cell, B-cell, and T&B cell knockout mice to elucidate the role of immune cells in sepsis. Flow cytometry was used to validate the mouse models, and the pathology can confirm renal tubular injury. LPS-induced sepsis caused significant renal pathological damage, Second-generation gene sequencing showed T cells-associated pathway was enriched in sepsis. The renal tubular injury was significantly reduced in T cell and T&B cell knockout mice (BALB/c-nu, Rag1-/-), especially in BALB/c-nu mice, with a decrease in the secretion of inflammatory cytokines in the renal tissue after LPS injection. LPS injection did not produce the same effect after the knockout of B cells. We found that blocking T cells could alleviate inflammation and renal injury caused by sepsis, providing a promising strategy for controlling renal injury.

METTL3-dependent m6A methylation facilitates uterine receptivity and female fertility via balancing estrogen and progesterone signaling.

Infertility is a worldwide reproductive health problem and there are still many unknown etiologies of infertility. In recent years, increasing evidence emerged and confirmed that epigenetic regulation played a leading role in reproduction. However, the function of m6A modification in infertility remains unknown. Here we report that METTL3-dependent m6A methylation plays an essential role in female fertility via balancing the estrogen and progesterone signaling. Analysis of GEO datasets reveal a significant downregulation of METTL3 expression in the uterus of infertile women with endometriosis or recurrent implantation failure. Conditional deletion of Mettl3 in female reproductive tract by using a Pgr-Cre driver results in infertility due to compromised uterine endometrium receptivity and decidualization. m6A-seq analysis of the uterus identifies the 3'UTR of several estrogen-responsive genes with METTL3-dependent m6A modification, like Elf3 and Celsr2, whose mRNAs become more stable upon Mettl3 depletion. However, the decreased expression levels of PR and its target genes, including Myc, in the endometrium of Mettl3 cKO mice indicate a deficiency in progesterone responsiveness. In vitro, Myc overexpression could partially compensate for uterine decidualization failure caused by Mettl3 deficiency. Collectively, this study reveals the role of METTL3-dependent m6A modification in female fertility and provides insight into the pathology of infertility and pregnancy management.

METTL3-mediated m6A methylation orchestrates mRNA stability and dsRNA contents to equilibrate γδ T1 and γδ T17 cells.

γδ T cells make key contributions to tissue physiology and immunosurveillance through two main functionally distinct subsets, γδ T1 and γδ T17. m6A methylation plays critical roles in controlling numerous aspects of mRNA metabolism that govern mRNA turnover, gene expression, and cellular functional specialization; however, its role in γδ T cells remains less well understood. Here, we find that m6A methylation controls the functional specification of γδ T17 vs. γδ T1 cells. Mechanistically, m6A methylation prevents the formation of endogenous double-stranded RNAs and promotes the degradation of Stat1 transcripts, which converge to prevent over-activation of STAT1 signaling and ensuing inhibition of γδ T17. Deleting Mettl3, the key enzyme in the m6A methyltransferases complex, in γδ T cells reduces interleukin-17 (IL-17) production and ameliorates γδ T17-mediated psoriasis. In summary, our work shows that METTL3-mediated m6A methylation orchestrates mRNA stability and double-stranded RNA (dsRNA) contents to equilibrate γδ T1 and γδ T17 cells.

Transcription factor TOX maintains the expression of Mst1 in controlling the early mouse NK cell development.

Rationale: TOX is a DNA-binding factor required for the development of multiple immune cells and the formation of lymph nodes. However, the temporal regulation mode of TOX on NK cell development and function needs to be further explored. Methods: To investigate the role of TOX in NK cells at distinct developmental phases, we deleted TOX at the hematopoietic stem cell stage (Vav-Cre), NK cell precursor (CD122-Cre) stage and late NK cell developmental stage (Ncr1-Cre), respectively. Flow cytometry was used to detect the development and functional changes of NK cell when deletion of TOX. RNA-seq was used to assess the differences in transcriptional expression profile of WT and TOX-deficient NK cells. Published Chip-seq data was exploited to search for the proteins directly interact with TOX in NK cells. Results: The deficiency of TOX at the hematopoietic stem cell stage severely retarded NK cell development. To a less extent, TOX also played an essential role in the physiological process of NKp cells differentiation into mature NK cells. Furthermore, the deletion of TOX at NKp stage severely impaired the immune surveillance function of NK cells, accompanied by down-regulation of IFN-γ and CD107a expression. However, TOX is dispensable for mature NK cell development and function. Mechanistically, by combining RNA-seq data with published TOX ChIP-seq data, we found that the inactivation of TOX at NKp stage directly repressed the expression of Mst1, an important intermediate kinase in Hippo signaling pathway. Mst1 deficient at NKp stage gained the similar phenotype with Toxfl/flCD122Cre mice. Conclusion: In our study, we conclude that TOX coordinates the early mouse NK cell development at NKp stage by maintaining the expression of Mst1. Moreover, we clarify the different dependence of the transcription factor TOX in NK cells biology.

mTORC1 signaling pathway integrates estrogen and growth factor to coordinate vaginal epithelial cells proliferation and differentiation.

The mouse vaginal epithelium cyclically exhibits cell proliferation and differentiation in response to estrogen. Estrogen acts as an activator of mTOR signaling but its role in vaginal epithelial homeostasis is unknown. We analyzed reproductive tract-specific Rptor or Rictor conditional knockout mice to reveal the role of mTOR signaling in estrogen-dependent vaginal epithelial cell proliferation and differentiation. Loss of Rptor but not Rictor in the vagina resulted in an aberrant proliferation of epithelial cells and failure of keratinized differentiation. As gene expression analysis indicated, several estrogen-mediated genes, including Pgr and Ereg (EGF-like growth factor) were not induced by estrogen in Rptor cKO mouse vagina. Moreover, supplementation of EREG could activate the proliferation and survival of vaginal epithelial cells through YAP1 in the absence of Rptor. Thus, mTORC1 signaling integrates estrogen and growth factor signaling to mediate vaginal epithelial cell proliferation and differentiation, providing new insights into vaginal atrophy treatment for post-menopausal women.

Microbial DNA enrichment promotes liver steatosis and fibrosis in the course of non-alcoholic steatohepatitis.

AIM: Low-grade inflammation is the hallmark of non-alcoholic fatty liver diseases (NAFLD) and non-alcoholic steatohepatitis (NASH). The leakage of microbiota-derived products can contribute to liver inflammation during NAFLD/NASH development. Here, we assessed the roles of gut microbial DNA-containing extracellular vesicles (mEVs) in regulating liver cellular abnormalities in the course of NAFLD/NASH. METHODS: We performed studies with Vsig4-/- , C3-/- , cGAS-/- , and their wild-type littermate mice. Vsig4+ macrophage population and bacterial DNA abundance were examined in both mouse and human liver by either flow cytometric or immunohistochemistry analysis. Gut mEVs were adoptively transferred into Vsig4-/- , C3-/- , cGAS-/- , or littermate WT mice, and hepatocyte inflammation and HSC fibrogenic activation were measured in these mice. RESULTS: Non-alcoholic fatty liver diseases and non-alcoholic steatohepatitis development was concomitant with a diminished liver Vsig4+ macrophage population and a marked bacterial DNA enrichment in both hepatocytes and HSCs. In the absence of Vsig4+ macrophages, gut mEVs translocation led to microbial DNA accumulation in hepatocytes and HSCs, resulting elevated hepatocyte inflammation and HSC fibrogenic activation. In contrast, in lean WT mice, Vsig4+ macrophages remove gut mEVs from bloodstream through a C3-dependent opsonization mechanism and prevent the infiltration of gut mEVs into hepatic cells. Additionally, Vsig4-/- mice more quickly developed significant liver steatosis and fibrosis than WT mice after Western diet feeding. In vitro treatment with NASH mEVs triggered hepatocyte inflammation and HSC fibrogenic activation. Microbial DNAs are key cargo for the effects of gut mEVs by activating cGAS/STING. CONCLUSION: Accumulation of microbial DNAs fuels the development of NAFLD/NASH-associated liver abnormalities.

SLAMF3 and SLAMF4 are immune checkpoints that constrain macrophage phagocytosis of hematopoietic tumors.

The interaction of SIRPα with CD47 represents a major mechanism for preventing macrophage phagocytosis. However, CD47-independent mechanisms are poorly defined. Here, we report a critical role of SLAM family receptors (SFRs), ubiquitously expressed on hematopoietic cells and forming homotypic interactions, in constraining macrophage phagocytosis. We found that SFR deficiency triggered macrophage phagocytosis of hematopoietic cells, leading to severe rejection of donor hematopoietic graft in recipient mice. Specific SFR members, mainly SLAMF3 and SLAMF4, were identified as "don't eat me" receptors on macrophages. These receptors inhibited "eat me" signals, such as LRP1-mediated activation of mTOR and Syk, through SH2 domain-containing phosphatases. SFRs combined with, but were independent of, CD47 to mitigate macrophage phagocytosis, and the combined deletion of SFRs and CD47 resulted in hematopoietic cytopenia in mice. This SFR-mediated tolerance was compromised in patients with hemophagocytic lymphohistiocytosis, a syndrome characterized by inappropriate phagocytosis toward hematopoietic cells. Loss of SFRs potently elicited macrophage rejection of hematopoietic tumors. Deletion of SFRs also significantly enhanced the phagocytosis of CD19-positive hematopoietic targets by the macrophages expressing the chimeric CD19 antigen receptor. Therefore, SFR-mediated inhibition of macrophage phagocytosis is critical to hematopoietic homeostasis, and SFRs may represent previously unknown targets for tumor immunotherapy.

Enhancing the therapeutic efficacy of programmed death ligand 1 antibody for metastasized liver cancer by overcoming hepatic immunotolerance in mice.

BACKGROUND AND AIMS: Immunotherapy with programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade has shown low response rates in liver cancer patients, with the underlying mechanisms unclear. To decipher a specific impact of the liver microenvironment, we compared the effects of anti-PD-L1 antibody (αPD-L1) blockade on the same tumor grown s.c. or in the liver. APPROACH AND RESULTS: We generated s.c. tumors in mice by inoculating MC38 colorectal cancer (CRC) cells under the skin and metastatic liver tumors by portal vein or splenic injection of CRC cells. Tumor-bearing mice were treated by i.p. injection of αPD-L1, polyinosinic:polycytidylic acid (poly[I:C]), or both. αPD-L1 monotherapy significantly suppressed s.c. tumor growth, but showed no effect on metastatic liver tumors. However, the combination of αPD-L1 with poly(I:C), an innate immunity-stimulating reagent, robustly inhibited tumor progression in liver. The combination therapy effectively down-regulated myeloid-derived suppressor cells (MDSCs), but up-regulated ratios of M1/M2 macrophages, CD8/CD4, and CD8/regulatory T (Treg) cells infiltrated into liver tumors and whole liver. A group of long-lasting T-bet+ Eomes- PD-1- cytotoxic T cells was maintained in the combo-treated liver, leading to resistance to tumor recurrence. Depleting macrophages or blocking type Ⅰ interferon signaling abrogated the synergistic antitumor effect of αPD-L1 and poly(I:C), indicating a requirement of boosting innate immunity for optimized activation of cytotoxic T cells by PD-1/PD-L1 blockade. CONCLUSIONS: The poor response of liver cancers to αPD-L1 therapy is largely attributable to a unique hepatic immunotolerant microenvironment, independent of tumor origins or types. The success of a combinatorial immunotherapy relies on coordinated inhibition or activation of various innate and adaptive immune cell activities.

Concurrent Disruption of the Ras/MAPK and NF-κB Pathways Induces Circadian Deregulation and Hepatocarcinogenesis.

The Ras/Erk and NF-κB pathways play critical roles in cell proliferation and are known to drive oncogenesis when overactivated. Herein we report a gatekeeper function of the two pathways by working in synergy to suppress liver tumorigenesis. Hepatocyte-specific deletion of both Shp2/Ptpn11 and Ikkß in mice, which promote Ras/Erk and NF-κB signaling, respectively, exacerbated chemical carcinogenesis and even triggered spontaneous development of hepatocellular carcinoma (HCC). We show that the unanticipated severe tumor phenotype was contributed collectively by severe cholestasis, metabolic changes, upregulated cell-cycle progression, and disruption of circadian rhythm in mutant hepatocytes. Remarkably, human HCCs with dysregulated circadian gene expression displayed downregulation of Ras/Erk and NF-κB signaling and poor prognosis. Together, these data indicate that at the ground state, the two central pathways, previously known as oncogenic, cooperate to sustain tumor-suppressive physiologic homeostasis and to prevent hepatic damage. Disruption of this intricate signaling network is carcinogenic in the liver. IMPLICATIONS: We demonstrate here that basal levels of the Ras/MAPK and NF-κB pathways, while promoting tumorigenesis if overactivated, are required to maintain physiologic homeostasis and regulate circadian rhythm in the liver, which are antitumorigenic.

The kinase PDK1 regulates regulatory T cell survival via controlling redox homeostasis.

Rationale: Regulatory T cells (Treg cells) play an important role in maintaining peripheral tolerance by suppressing over-activation of effector T cells. The kinase PDK1 plays a pivotal role in conventional T cell development. However, whether PDK1 signaling affects the homeostasis and function of Treg cells remains elusive. Methods: In order to evaluate the role of PDK1 in Treg cells from a genetic perspective, mice carrying the floxed PDK1 allele were crossbred with Foxp3Cre mice to efficiently deleted PDK1 in Foxp3+ Treg cells. Flow cytometry was used to detect the immune cell homeostasis of WT and PDK1fl/flFoxp3Cre mice. RNA-seq was used to assess the differences in transcriptional expression profile of WT and PDK1-deficient Treg cells. The metabolic profiles of WT and PDK1-deficient Treg cells were tested using the Glycolysis Stress Test and Mito Stress Test Kits by the Seahorse XFe96 Analyser. Results: PDK1 was essential for the establishment and maintenance of Treg cell homeostasis and function. Disruption of PDK1 in Treg cells led to a spontaneous fatal systemic autoimmune disorder and multi-tissue inflammatory damage, accompanied by a reduction in the number and function of Treg cells. The deletion of PDK1 in Treg cells destroyed the iron ion balance through regulating MEK-ERK signaling and CD71 expression, resulting in excessive production of intracellular ROS, which did not depend on the down-regulation of mTORC1 signaling. Inhibition of excessive ROS, activated MEK-Erk signaling or overload Fe2+ could partially rescue the survival of PDK1-deficient Treg cells. Conclusion: Our results defined a key finding on the mechanism by which PDK1 regulates Treg cell survival via controlling redox homeostasis.

Hepatocyte-derived exosomes from early onset obese mice promote insulin sensitivity through miR-3075.

In chronic obesity, hepatocytes become insulin resistant and exert important effects on systemic metabolism. Here we show that in early onset obesity (4 weeks high-fat diet), hepatocytes secrete exosomes that enhance insulin sensitivity both in vitro and in vivo. These beneficial effects were due to exosomal microRNA miR-3075, which is enriched in these hepatocyte exosomes. FA2H is a direct target of miR-3075 and small interfering RNA depletion of FA2H in adipocytes, myocytes and primary hepatocytes leads to increased insulin sensitivity. In chronic obesity (16-18 weeks of a high-fat diet), hepatocyte exosomes promote a state of insulin resistance. These chronic obese hepatocyte exosomes do not directly cause impaired insulin signalling in vitro but do promote proinflammatory activation of macrophages. Taken together, these studies show that in early onset obesity, hepatocytes produce exosomes that express high levels of the insulin-sensitizing miR-3075. In chronic obesity, this compensatory effect is lost and hepatocyte-derived exosomes from chronic obese mice promote insulin resistance.

mTORC1 and mTORC2 coordinate early NK cell development by differentially inducing E4BP4 and T-bet.

Natural killer (NK) cell development is a multistep process that requires a variety of signals and transcription factors. The lack of mammalian target of rapamycin (mTOR) kinase severely impairs NK cell development in mice. mTOR binds to Raptor and Rictor to form two complexes, mTORC1 and mTORC2, respectively. How mTOR and its two complexes regulate NK cell development is not fully understood. Here, we developed two methods to inactivate mTOR, Raptor, or Rictor in early stage NK cells (using CD122-Cre) or in late-stage NK cells (using Ncr1-CreTg). First, we found that when mTOR was deleted by CD122-Cre during and after NK cell commitment, NK cell development was severely impaired, while Ncr1-CreTg mediated mTOR deletion slightly affected NK cell terminal differentiation, suggesting that mTOR is essential for early NK cell differentiation. Second, we found that CD122-mediated deletion of Raptor significantly limited the differentiation of CD27+CD11b- immature NK (iNK) cell into mature NK cells. In contrast, the absence of Rictor significantly interfered with the differentiation of CD27-CD11b- early iNK cells. Third, Ncr1-mediated deletion of Raptor, rather than Rictor, moderately affected NK cell terminal differentiation. In terms of mechanism, mTORC1 mainly promotes the expression of NK cell-specific transcription factor E4 promoter-binding protein 4 (E4BP4), while both mTORC1 and mTORC2 can enhance the expression of T-bet. Therefore, mTORC1 and mTORC2 subtly coordinate NK cell development by differentially inducing E4BP4 and T-bet.

Roles of mTORC1 and mTORC2 in controlling γδ T1 and γδ T17 differentiation and function.

The metabolism-controlled differentiation of αß T cells has been well documented; however, the role of a metabolism program in γδ T cell differentiation and function has not been clarified. Here, using CD2-cre; mTORC1 Raptor-f/f, and mTORC2 Rictor-f/f mice (KO mice), we found that mTORC1, but not mTORC2, was required for the proliferation and survival of peripheral γδ T cells, especially Vγ4 γδ T cells. Moreover, mTORC1 was essential for both γδ T1 and γδ Τ17 differentiation, whereas mTORC2 was required for γδ T17, but not for γδ Τ1, differentiation. We further studied the underlying molecular mechanisms and found that depletion of mTORC1 resulted in the increased expression of SOCS1, which in turn suppressed the key transcription factor Eomes, consequentially reducing IFN-γ production. Whereas the reduced glycolysis resulted in impaired γδ Τ17 differentiation in Raptor KO γδ T cells. In contrast, mTORC2 potentiated γδ Τ17 induction by suppressing mitochondrial ROS (mitoROS) production. Consistent with their cytokine production profiles, the Raptor KO γδ T cells lost their anti-tumor function both in vitro and in vivo, whereas both Raptor and Rictor KO mice were resistant to imiquimod (IMQ)-induced psoriasis-like skin pathogenesis. In summary, we identified previously unknown functions of mTORC1 and mTORC2 in γδ T cell differentiation and clarified their divergent roles in mediating the activity of γδ T cells in tumors and autoimmunity.

pH-stimulus response dye-cucurbituril sensor for amino acids in aqueous solution.

The host-guest inclusion complexes that comprise an inverted cucurbit[7]uril (iQ[7]) and a quinoline derivative, 4-(4-dimethylaminostyryl) quinoline (DSQ) at different pHs were exploited as multiple supramolecular sensors to sense l-α-amino acids. DSQ complexation inside iQ[7] at different pHs leads to increased fluorescence and formation of different-colored iQ[7]-DSQ complexes. The enhanced fluorescence of DSQ after iQ[7] encapsulation may be attributed to limited dimethylamine rotation and the formation of a twisted internal charge transfer (TICT) state. The DSQ@iQ[7] sensors have different affinities for l-α-amino acids at different pHs. Therefore, we propose a pH-stimulus response supramolecular sensor for the discrimination of structurally similar l-α-amino acids in aqueous solution.

Early Administration of Oseltamivir Within 48 Hours After Onset of Flulike Symptoms Can Reduce the Risk of Influenza B Virus-Associated Pneumonia in Hospitalized Pediatric Patients with Influenza B Virus Infection.

We conducted a retrospective study to identify the risk factors for pneumonia in hospitalized pediatric patients with influenza B infection. Receiving oseltamivir within the first 48 hours of onset and frequent cough was respectively considered as a protective factor and a risk factor for the influenza B virus-associated pneumonia in hospitalized pediatric patients. Early administration of oseltamivir can reduce the risk of influenza B virus-associated pneumonia.

Full Activation of Kinase Protein Kinase B by Phosphoinositide-Dependent Protein Kinase-1 and Mammalian Target of Rapamycin Complex 2 Is Required for Early Natural Killer Cell Development and Survival.

The role of PI3K-mTOR pathway in regulating NK cell development has been widely reported. However, it remains unclear whether NK cell development depends on the protein kinase B (PKB), which links PI3K and mTOR, perhaps due to the potential redundancy of PKB. PKB has two phosphorylation sites, threonine 308 (T308) and serine 473 (S473), which can be phosphorylated by phosphoinositide-dependent protein kinase-1 (PDK1) and mTORC2, respectively. In this study, we established a mouse model in which PKB was inactivated through the deletion of PDK1 and Rictor, a key component of mTORC2, respectively. We found that the single deletion of PDK1 or Rictor could lead to a significant defect in NK cell development, while combined deletion of PDK1 and Rictor severely hindered NK cell development at the early stage. Notably, ectopic expression of myristoylated PKB significantly rescued this defect. In terms of mechanism, in PDK1/Rictor-deficient NK cells, E4BP4, a transcription factor for NK cell development, was less expressed, and the exogenous supply of E4BP4 could alleviate the developmental defect of NK cell in these mice. Besides, overexpression of Bcl-2 also helped the survival of PDK1/Rictor-deficient NK cells, suggesting an anti-apoptotic role of PKB in NK cells. In summary, complete phosphorylation of PKB at T308 and S473 by PDK1 and mTORC2 is necessary for optimal NK cell development, and PKB regulates NK cell development by promoting E4BP4 expression and preventing cell apoptosis.