Molecular targets and mechanisms of different aberrant alternative splicing in metastatic liver cancer

Metastasis remains a major challenge in the successful management of malignant diseases. The liver is a major site of metastatic disease and a leading cause of death from gastrointestinal malignancies such as colon, stomach, and pancreatic cancers, as well as melanoma, breast cancer, and sarcoma. As an important factor that influences the development of metastatic liver cancer, alternative splicing drives the diversity of RNA transcripts and protein subtypes, which may provide potential to broaden the target space. In particular, the dysfunction of splicing factors and abnormal expression of splicing variants are associated with the occurrence, progression, aggressiveness, and drug resistance of cancers caused by the selective splicing of specific genes. This review is the first to provide a detailed summary of the normal splicing process and alterations that occur during metastatic liver cancer. It will cover the role of alternative splicing in the mechanisms of metastatic liver cancer by examining splicing factor changes, abnormal splicing, and the contribution of hypoxia to these changes during metastasis.

Azide-modified corrole phosphorus complexes for endoplasmic reticulum-targeted fluorescence bioimaging and effective cancer photodynamic therapy

Study on corrole photosensitizers (PSs) for photodynamic therapy (PDT) has made remarkable progress. Targeted delivery of PSs is of great significance for enhancing therapeutic efficiency, decreasing the dosage, and reducing systemic toxicity during PDT. The development of PSs that can be specifically delivered to the subcellular organelle is still an attractive and challenging work. Herein, we synthesize a series of azide-modified corrole phosphorus and gallium complex PSs, in which phosphorus corrole 2-P could not only precisely target the endoplasmic reticulum (ER) with a Pearson correlation coefficient (PCC) up to 0.92 but also possesses the highest singlet oxygen quantum yields (ΦΔ = 0.75). This renders it remarkable PDT activity at a very low dosage (IC50 = 23 nM) towards HepG2 tumor cell line while ablating solid tumors in vivo with excellent biosecurity. Furthermore, 2-P exhibits intense red fluorescence (ΦF = 0.25), outstanding photostability, and a large Stokes shift (190 nm), making it a promising fluorescent probe for ER. This study provides a clinically potential photosensitizer for cancer photodynamic therapy and a promising ER fluorescent probe for bioimaging.

Loss of Diacylglycerol Kinase α Enhances Macrophage Responsiveness

The diacylglycerol kinases (DGKs) are a family of enzymes responsible for the conversion of diacylglycerol (DAG) to phosphatidic acid (PA). In addition to their primary function in lipid metabolism, DGKs have recently been identified as potential therapeutic targets in multiple cancers, including glioblastoma (GBM) and melanoma. Aside from its tumorigenic properties, DGKα is also a known promoter of T-cell anergy, supporting a role as a recently-recognized T cell checkpoint. In fact, the only significant phenotype previously observed in Dgka knockout (KO) mice is the enhancement of T-cell activity. Herein we reveal a novel, macrophage-specific, immune-regulatory function of DGKα. In bone marrow-derived macrophages (BMDMs) cultured from wild-type (WT) and KO mice, we observed increased responsiveness of KO macrophages to diverse stimuli that yield different phenotypes, including LPS, IL-4, and the chemoattractant MCP-1. Knockdown (KD) of Dgka in a murine macrophage cell line resulted in similar increased responsiveness. Demonstrating in vivo relevance, we observed significantly smaller wounds in Dgka^-/- mice with full-thickness cutaneous burns, a complex wound healing process in which macrophages play a key role. The burned area also demonstrated increased numbers of macrophages. In a cortical stab wound model, Dgka^-/- brains show increased Iba1⁺ cell numbers at the needle track versus that in WT brains. Taken together, these findings identify a novel immune-regulatory checkpoint function of DGKα in macrophages with potential implications for wound healing, cancer therapy, and other settings.

Cezanne enhances epithelial mesenchymal transition and prevents anthracycline-induced apoptosis via AKT/mTOR signaling in hepatocellular carcinoma.. [DOI: 10.21203/rs.3.rs-676858/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background Anthracycline resistance have hindered the efficacy of transcatheter arterial chemoembolization (TACE). Translational research is therefore in need to find potential combinations by studying the resistance mechanism of anthracycline. In our published work, we found Cezanne could predict the efficacy of adjuvant TACE (ad-TACE) and induce epithelium mesenchymal transition (EMT) in hepatocellular carcinoma (HCC). We hereby conduct a sequential investigation to reveal the role of Cezanne on EMT and its potential to retard resistance. Methods The response of Cezanne in patients treated with adjuvant TACE after hepatectomy was evaluated. Functional assays were used to examine the resistance function of Cezanne to anthracyclin. In-situ tumorigenesis models and intraperitoneal perfusion chemotherapy experiment were used for in vivo verification. Results High expression of Cezanne correlated to a better outcome. Multivariate analysis showed low expression of Cezanne and the application of postoperative ad-TACE therapy were independent prognostic risk factors. However, patient outcome was significantly shorter in high Cezanne group of ad-TACE patients. In vitro assays revealed that HCC functions were inhibited after overexpressing Cezanne (OE-Cezanne). After treated with epirubicin, however, OE-Cezanne cell lines did not respond to treatment. In vivo experiment was consistent with in vitro assays. Besides, high Cezanne transforms cell morphology and is correlated to the activation of EMT related genes. Gene set analysis showed that Cezanne can regulate PI3K/AKT/mTOR signaling pathway. Therefore, mTOR inhibitor Rapamycin can reverse the resisting effect of Cezanne on HCC cell lines. Conclusions Adjuvant anthracycline-based TACE treatment after curative surgery can reduce the recurrence rate in HCC patients. However, in patients with high Cezanne expression, the efficacy of TACE may be undermined by EMT inducement. We discovered Cezanne modulates EMT by activating the AKT/mTOR signaling pathway and provided evidence for the rationale of combining mTOR inhibitor with TACE to prevent recurrence in HCC patients.

Regulation of Intrinsic and Bystander T Follicular Helper Cell Differentiation and Autoimmunity by Tsc1

T Follicular helper (Tfh) cells promote germinal center (GC) B cell responses to develop effective humoral immunity against pathogens. However, dysregulated Tfh cells can also trigger autoantibody production and the development of autoimmune diseases. We report here that Tsc1, a regulator for mTOR signaling, plays differential roles in Tfh cell/GC B cell responses in the steady state and in immune responses to antigen immunization. In the steady state, Tsc1 in T cells intrinsically suppresses spontaneous GC-Tfh cell differentiation and subsequent GC-B cell formation and autoantibody production. In immune responses to antigen immunization, Tsc1 in T cells is required for efficient GC-Tfh cell expansion, GC-B cell induction, and antigen-specific antibody responses, at least in part via promoting GC-Tfh cell mitochondrial integrity and survival. Interestingly, in mixed bone marrow chimeric mice reconstituted with both wild-type and T cell-specific Tsc1-deficient bone marrow cells, Tsc1 deficiency leads to enhanced GC-Tfh cell differentiation of wild-type CD4 T cells and increased accumulation of wild-type T regulatory cells and T follicular regulatory cells. Such bystander GC-Tfh cell differentiation suggests a potential mechanism that could trigger self-reactive GC-Tfh cell/GC responses and autoimmunity via neighboring GC-Tfh cells.

Differential controls of MAIT cell effector polarization by mTORC1/mTORC2 via integrating cytokine and costimulatory signals

Mucosal-associated invariant T (MAIT) cells have important functions in immune responses against pathogens and in diseases, but mechanisms controlling MAIT cell development and effector lineage differentiation remain unclear. Here, we report that IL-2/IL-15 receptor β chain and inducible costimulatory (ICOS) not only serve as lineage-specific markers for IFN-γ-producing MAIT1 and IL-17A-producing MAIT17 cells, but are also important for their differentiation, respectively. Both IL-2 and IL-15 induce mTOR activation, T-bet upregulation, and subsequent MAIT cell, especially MAIT1 cell, expansion. By contrast, IL-1β induces more MAIT17 than MAIT1 cells, while IL-23 alone promotes MAIT17 cell proliferation and survival, but synergizes with IL-1β to induce strong MAIT17 cell expansion in an mTOR-dependent manner. Moreover, mTOR is dispensable for early MAIT cell development, yet pivotal for MAIT cell effector differentiation. Our results thus show that mTORC2 integrates signals from ICOS and IL-1βR/IL-23R to exert a crucial role for MAIT17 differentiation, while the IL-2/IL-15R-mTORC1-T-bet axis ensures MAIT1 differentiation.

Thymic Epithelial Cell-Derived IL-15 and IL-15 Receptor α Chain Foster Local Environment for Type 1 Innate Like T Cell Development

Expression of tissue-restricted antigens (TRAs) in thymic epithelial cells (TECs) ensures negative selection of highly self-reactive T cells to establish central tolerance. Whether some of these TRAs could exert their canonical biological functions to shape thymic environment to regulate T cell development is unclear. Analyses of publicly available databases have revealed expression of transcripts at various levels of many cytokines and cytokine receptors such as IL-15, IL-15Rα, IL-13, and IL-23a in both human and mouse TECs. Ablation of either IL-15 or IL-15Rα in TECs selectively impairs type 1 innate like T cell, such as iNKT1 and γδT1 cell, development in the thymus, indicating that TECs not only serve as an important source of IL-15 but also trans-present IL-15 to ensure type 1 innate like T cell development. Because type 1 innate like T cells are proinflammatory, our data suggest the possibility that TEC may intrinsically control thymic inflammatory innate like T cells to influence thymic environment.

Negative control of diacylglycerol kinase ζ-mediated inhibition of T cell receptor signaling by nuclear sequestration in mice

Diacylglycerol kinases (DGKs) play important roles in restraining diacylglycerol (DAG)-mediated signaling. Within the DGK family, the ζ isoform appears to be the most important isoform in T cells for controlling their development and function. DGKζ has been demonstrated to regulate T cell maturation, activation, anergy, effector/memory differentiation, defense against microbial infection, and antitumor immunity. Given its critical functions, DGKζ function should be tightly regulated to ensure proper signal transduction; however, mechanisms that control DGKζ function are still poorly understood. We report here that DGKζ dynamically translocates from the cytosol into the nuclei in T cells after TCR stimulation. In mice, DGKζ mutant defective in nuclear localization displayed enhanced ability to inhibit TCR-induced DAG-mediated signaling in primary T cells, maturation of conventional αβT and iNKT cells, and activation of peripheral T cells compared with WT DGKζ. Our study reveals for the first time nuclear sequestration of DGKζ as a negative control mechanism to spatially restrain it from terminating DAG mediated signaling in T cells. Our data suggest that manipulation of DGKζ nucleus-cytosol shuttling as a novel strategy to modulate DGKζ activity and immune responses for treatment of autoimmune diseases and cancer.

MxA suppresses TAK1-IKKα/β-NF-κB mediated inflammatory cytokine production to facilitate Mycobacterium tuberculosis infection

OBJECTIVES

Interferons (IFNs) play multifunctional roles in host defense against infectious diseases by inducing IFN-stimulated genes (ISGs). However, little is known about how ISGs regulate host immune response to Mycobacterium tuberculosis (Mtb) infection, the major cause of tuberculosis (TB).

METHODS

We thus profiled the potential effects and mechanisms of eight Mtb-induced ISGs on Mtb infection by RNA interference in human macrophages (Mφs) derived from peripheral blood monocytes (hMDMs) and THP-1 cell line derived Mφs (THP-1-Mφs).

RESULTS

MxA silencing significantly decreased intracellular Mtb infection in Mφs. Mechanistically, MxA silencing promoted inflammatory cytokines IL-1β, IL-6 and TNF-α production, and induced NF-κB p65 activation. Pharmacological inhibition of NF-κB p65 activation or gene silencing of NF-κB p65 blocked the increased production of IL-1β, IL-6 and TNF-α and restored Mtb infection by MxA silencing. Furthermore, pharmacological inhibition of TAK1 and IKKα/β blocked NF-κB p65 activation and subsequent production of pro-inflammatory cytokines by MxA silencing. Isoniazid (INH) treatment and MxA silencing could promote TAK1-IKKα/β-NF-κB signaling pathway activation and combat Mtb infection independently.

CONCLUSIONS

Our results reveal a novel role of MxA in regulating TAK1-IKKα/β-NF-κB signaling activation and production of antimicrobial inflammatory cytokines upon Mtb infection, providing a potential target for clinical treatment of TB.

Thymic Epithelial Cells Contribute to Thymopoiesis and T Cell Development

The thymus is the primary lymphoid organ responsible for the generation and maturation of T cells. Thymic epithelial cells (TECs) account for the majority of thymic stromal components. They are further divided into cortical and medullary TECs based on their localization within the thymus and are involved in positive and negative selection, respectively. Establishment of self-tolerance in the thymus depends on promiscuous gene expression (pGE) of tissue-restricted antigens (TRAs) by TECs. Such pGE is co-controlled by the autoimmune regulator (Aire) and forebrain embryonic zinc fingerlike protein 2 (Fezf2). Over the past two decades, research has found that TECs contribute greatly to thymopoiesis and T cell development. In turn, signals from T cells regulate the differentiation and maturation of TECs. Several signaling pathways essential for the development and maturation of TECs have been discovered. New technology and animal models have provided important observations on TEC differentiation, development, and thymopoiesis. In this review, we will discuss recent advances in classification, development, and maintenance of TECs and mechanisms that control TEC functions during thymic involution and central tolerance.

DGK α and ζ Activities Control TH1 and TH17 Cell Differentiation

CD4⁺ T helper (T_H) cells are critical for protective adaptive immunity against pathogens, and they also contribute to the pathogenesis of autoimmune diseases. How T_H differentiation is regulated by the TCR's downstream signaling is still poorly understood. We describe here that diacylglycerol kinases (DGKs), which are enzymes that convert diacylglycerol (DAG) to phosphatidic acid, exert differential effects on T_H cell differentiation in a DGK dosage-dependent manner. A deficiency of either DGKα or ζ selectively impaired T_H1 differentiation without obviously affecting T_H2 and T_H17 differentiation. However, simultaneous ablation of both DGKα and ζ promoted T_H1 and T_H17 differentiation in vitro and in vivo, leading to exacerbated airway inflammation. Furthermore, we demonstrate that dysregulation of T_H17 differentiation of DGKα and ζ double-deficient CD4⁺ T cells was, at least in part, caused by increased mTOR complex 1/S6K1 signaling.

Differential Control of iNKT Cell Effector Lineage Differentiation by the Forkhead Box Protein O1 (Foxo1) Transcription Factor

The invariant NKT (iNKT) cells recognize glycolipid antigens presented by the non-classical MHC like molecule CD1d. They represent an innate T-cell lineage with the ability to rapidly produce a variety of cytokines in response to agonist stimulation to bridge innate and adaptive immunity. In thymus, most iNKT cells complete their maturation and differentiate to multiple effector lineages such as iNKT-1, iNKT-2, and iNKT-17 cells that possess the capability to produce IFNγ, IL-4, and IL-17A, respectively, and play distinct roles in immune responses and diseases. Mechanisms that control iNKT lineage fate decisions are still not well understood. Evidence has revealed critical roles of Foxo1 of the forkhead box O1 subfamily of transcription factors in the immune system. However, its role in iNKT cells has been unknown. In this report, we demonstrate that deletion of Foxo1 causes severe decreases of iNKT cell total numbers due to impairment of late but not early iNKT cell development. Deficiency of Foxo1 results in decreases of iNKT-1 but increases of iNKT-17 cells. Our data reveal that Foxo1 controls iNKT effector lineage fate decision by promoting iNKT-1 but suppressing iNKT-17 lineages.

Graded diacylglycerol kinases α and ζ activities ensure mucosal-associated invariant T-cell development in mice

Mucosal-associated invariant T (MAIT) cells participate in both protective immunity and pathogenesis of diseases. Most murine MAIT cells express an invariant TCRVα19-Jα33 (iVα19) TCR, which triggers signals crucial for their development. However, signal pathways downstream of the iVα19TCR and their regulation in MAIT cells are unknown. Diacylglycerol (DAG) is a critical second messenger that relays the TCR signal to multiple downstream signaling cascades. DAG is terminated by DAG kinase (DGK)-mediated phosphorylation and conversion to phosphatidic acid. We have demonstrated here that downregulation of DAG caused by enhanced DGK activity impairs late-stage MAIT cell maturation in both thymus and spleen. Moreover, deficiency of DGKζ but not DGKα by itself causes modest decreases in MAIT cells, and deficiency of both DGKα and ζ results in severe reductions of MAIT cells in an autonomous manner. Our studies have revealed that DAG signaling is not only critical but also must be tightly regulated by DGKs for MAIT cell development and that both DGKα and, more prominently, DGKζ contribute to the overall DGK activity for MAIT cell development.

Platelet-albumin-bilirubin grade: Risk stratification of liver failure, prognosis after resection for hepatocellular carcinoma

BACKGROUND AND AIMS

The liver function reserve in Child-Pugh (C-P) grade A hepatocellular carcinoma (HCC) patients varies widely, and the value of platelet-albumin-bilirubin (PALBI) grade in predicting posthepatectomy liver failure (PHLF) grade B/C and overall survival (OS) remains unknown.

METHODS

From Dec 2004 to Dec 2013, 2038 C-P grade A HCC patients after resection were enrolled. Univariate and multivariate analyses were performed to clarify the risk factors for PHLF grade B/C and OS.

RESULTS

The PALBI grade had higher area under the curve values than albumin-bilirubin (ALBI) and C-P grade in predicting PHLF grade B/C (0.693, 0.683, 0.529 in the entire cohort; 0.677, 0.646, 0.516 in patients who underwent major resection). PALBI grade differentiated C-P grade A patients into three groups with distinct prognoses (P < 0.001), whereas ALBI grade differentiated C-P grade A patients into two groups (P < 0.001). Furthermore, PALBI grade identified three groups with clearly different prognoses in ALBI grade 1 patients (P = 0.032). Multivariate analyses showed that PALBI grade was one of the independent and significant prognostic factors of PHLF grade B/C and OS.

CONCLUSIONS

PALBI grade offers a simple, objective and discriminatory method for risk stratification of PHLF grade B/C and OS in C-P grade A HCC patients following resection.

Efficient CD4Cre-Mediated Conditional KRas Expression in Alveolar Macrophages and Alveolar Epithelial Cells Causes Fatal Hyperproliferative Pneumonitis

The CD4Cre transgenic model has been widely used for T cell-specific gene manipulation. We report unexpected highly efficient Cre-mediated recombination in alveolar macrophages (AMFs), bronchial epithelial cells (BECs), and alveolar epithelial cells (AECs) in this strain of mice. Different from CD4 T cells, AMFs, AECs, and BECs do not express detectable Cre protein, suggesting that Cre protein is either very transiently expressed in these cells or only expressed in their precursors. Mice carrying a conditional constitutively active KRas (caKRas) allele and the CD4Cre transgene contain not only hyperactivated T cells but also develop severe AMF accumulation, AEC and BEC hyperplasia, and adenomas in the lung, leading to early lethality correlated with caKRas expression in these cells. We propose that caKRas-CD4Cre mice represent, to our knowledge, a novel model of proliferative pneumonitis involving macrophages and epithelial cells and that the CD4Cre model may offer unique usefulness for studying gene functions simultaneously in multilineages in the lung. Our observations, additionally, suggest that caution in data interpretation is warranted when using the CD4Cre transgenic model for T cell-specific gene manipulation, particularly when lung pathophysiological status is being examined.

Risk factors of extra-hepatic progression after transarterial chemoembolization for hepatocellular carcinoma patients: a retrospective study in 654 cases

Aim: To investigate the risk factors of extra-hepatic progression after TACE in HCC.

Methods: The study population included 654 HCC patients who underwent TACE between October 2005 and September 2012. We collected and analyzed their clinical characteristics and survival information. TACE was performed as previously described with minor modifications. When necessary, superselective chemoembolization was performed through the segmental or subsegmental arteries, based on the tumor location and extent and hepatic function reserve. If stasis could not be achieved in a tumor-feeding artery, iodized oil was used solely in some patients. Embolization was then performed with injection of absorbable gelfoam particles (1-2 mm in diameter) through the angiographic catheter.

Results: The tumor response to initial TACE was evaluated in 645 patients. The CR rate, response rate (RR), and disease control rate (DCR) were 9.92%, 25.89%, and 70.39%, respectively. The median overall survival (OS) period was 14.5 months. The 6-month, 1-, 2-, 3-, and 5-year OS rates were 75.5%, 55.0%, 33.9%, 22.8%, and 14.9%, respectively. The median progression-free survival (PFS) period was 4.3 months. The 6-month, 1-, 2-, 3-, and 5-year PFS rates were 40.7%, 27.1%, 16.7%, 13.9%, and 9.3%, respectively. One hundred and fifty patients developed extrahepatic progression during follow-up. We demonstrated that in the absence of radical treatment after initial TACE (p<0.001), the presence of extrahepatic metastasis before initial TACE (p<0.001), AST >45 U/L (p=0.024), ALB <35 g/L (p=0.012), and tumor response were evaluated as PD and SD after initial TACE (p<0.001) and were found to be independent predictors of a poorer prognosis of extrahepatic PFS.

Conclusions: We identified risk factors for extrahepatic progression after TACE in HCC patients. Early combination treatment was strongly recommended in patients that met these risk factors.

NLRC3 expression in dendritic cells attenuates CD4+ T cell response and autoimmunity

NOD-like receptor (NLR) family CARD domain containing 3 (NLRC3), an intracellular member of NLR family, is a negative regulator of inflammatory signaling pathways in innate and adaptive immune cells. Previous reports have shown that NLRC3 is expressed in dendritic cells (DCs). However, the role of NLRC3 in DC activation and immunogenicity is unclear. In the present study, we find that NLRC3 attenuates the antigen-presenting function of DCs and their ability to activate and polarize CD4⁺ T cells into Th1 and Th17 subsets. Loss of NLRC3 promotes pathogenic Th1 and Th17 responses and enhanced experimental autoimmune encephalomyelitis (EAE) development. NLRC3 negatively regulates the antigen-presenting function of DCs via p38 signaling pathway. Vaccination with NLRC3-overexpressed DCs reduces EAE progression. Our findings support that NLRC3 serves as a potential target for treating adaptive immune responses driving multiple sclerosis and other autoimmune disorders.

Deficiency of Mucosal-Associated Invariant T Cells in TCRJα18 Germline Knockout Mice

Mucosal-associated invariant T (MAIT) cells and invariant NK T (iNKT) cells account for the major lymphocyte populations that express invariant TCRα-chains. MAIT cells mostly express the TCRVα19-Jα33 TCR in mice and the TCRVα7.2-Jα33 TCR in humans, whereas iNKT cells express the TCRVα14-Jα18 TCR in mice and the TCRVα24-Jα18 TCR in humans. Both MAIT and iNKT cells have the capacity to quickly produce a variety of cytokines in response to agonist stimuli and to regulate both innate and adaptive immunity. The germline TCRJα18 knockout (Traj18^-/- ) mice have been used extensively for studying iNKT cells. Although it has been reported that the TCRα repertoire was narrowed and the level of Trav19-ja33 transcript was decreased in this strain of mice, direct assessment of MAIT cells in these mice has not been reported. We demonstrate in this study that this strain of mice is also defective of MAIT T cells, cautioning data interpretation when using this strain of mice.

NCKAP1 improves patient outcome and inhibits cell growth by enhancing Rb1/p53 activation in hepatocellular carcinoma

In our previous report, we identified miR-34c-3p as an independent factor contributing to the carcinogenesis of hepatocellular carcinoma (HCC) by targeting NCK Associated Protein 1 (NCKAP1). NCKAP1 has been known to promote the malignancy of cancer cells by disrupting the structural stability of WAS protein family member 1 (WASF1) and is correlated with poor prognosis of patients in several cancer types. Our results, however, show that NCKAP1 is correlated with a favorable outcome in HCC patients. The underlying mechanism of this contradictory phenomenon is unknown. The current study was designed to explore the mechanism of NCKAP1 in HCC. As a result, clinicopathological correlations and results from in vivo and in vitro models indicated that NCKAP1 was a tumor suppressor gene. Cell cycle analysis suggested that NCKAP1 inhibit cells from entering G2/M phase. Western blot analysis showed that WASF1 was barely expressed in HCC cell lines compared to that of breast cancer cell lines, which serve as positive controls. Furthermore, Rb1 and p53 expression was upregulated in cell lines overexpressing NCKAP1. Expression of several cell cycle regulating proteins also varied in the HCC cell lines. In conclusion, although previous studies have identified NCKAP1 as a cell invasion promoter by binding to WASF1, we found that NCKAP1 is a tumor suppress gene that modulates the cell cycle of HCC cell lines by targeting Rb1/p53 regulation.

Circulating Mucosal-Associated Invariant T Cells in a Large Cohort of Healthy Chinese Individuals From Newborn to Elderly

Mucosal-associated invariant T (MAIT) cells, which are enriched in human blood and express a semi-invariant TCR chain, play important roles in conditions such as infectious diseases and cancer. The influence of age on levels and functional characteristics of circulating MAIT cells have not been fully addressed. Here we have collected blood samples from a large cohort of healthy Chinese individuals from newborn (cord blood) to the elderly and assessed the levels of circulating MAIT cells as well as their phenotype, activation and apoptosis status, and cytokine expression profiles after in vitro stimulation. We found that the frequencies of circulating MAIT cells gradually increased in blood from newborns as they progressed into adulthood (20–40 years old) but then decreased during further progression toward old age (>60 years old). The lowered numbers of circulating MAIT cells in the elderly was correlated with a gradual increase of apoptosis. A majority of circulating MAIT cells expressed the chemokine receptors CCR5 and CCR6, and most also expressed CD8 and CD45RO. Few expressed CD69 in cord blood, but the frequency increased with age. Upon in vitro activation with PMA plus ionomycin or IL12 plus IL18, fewer MAIT cells isolated from the young adult group expressed IFN-γ, IL17A and Granzyme B then cells from other age groups while the proportion of cells that expressed TNF-α was similar. Taken together, our data provide information for guiding the assessment of normal levels and phenotypes of MAIT cells at different ages in healthy individuals and patients.

Anatomical versus Non-anatomical Resection for Hepatocellular Carcinoma with Microscope Vascular Invasion: A Propensity Score Matching Analysis

Background: The benefits of anatomical resection (AR) and non-anatomical resection (NAR) on hepatocellular carcinoma (HCC) patients with microscope vascular invasion (MVI) remain unknown. We aimed to investigate the prognostic outcomes of AR and NAR for HCC patients with MVI. Study Design: A total of 362 consecutive HCC patients diagnosed with MVI after hepatic resection between February 2005 and December 2013 were included in this study. The patient outcomes were compared, and a 1:2 propensity score matching (PSM) analysis was applied to eliminate selection bias. Results: Before PSM, compared to the NAR group, the AR group contained more patients that exceeded the Milan criteria, with larger, unilobar tumors and higher AST levels. After PSM, 100 patients were classified into the propensity-matched AR group (PS-AR), while 170 were classified into the propensity-matched NAR group (PS-NAR). Baseline data, including liver function and tumor burden measurements, were similar in the matched groups. The respective 1-, 3- and 5-year overall survival (OS) rates were 78.9%, 56.9%, and 51.5% in the PS-AR group and 76.2%, 53.0%, and 42.4% in the PS-NAR group (P = 0.301). The 1-, 3- and 5-year disease-free survival (DFS) rates were 51.1%, 44.7% and 42.0% in the PS-AR group and 44.9%, 34.3% and 26.4% in the PS-NAR group, respectively (P = 0.039). Multivariate analysis identified AR (P=0.025) as an independent favorable prognostic factor for DFS in HCC patients with MVI. Conclusions: Anatomical resection was superior to non-anatomical resection for improving DFS in hepatocellular carcinoma patients with microscope vascular invasion.

[Determination of acrylonitrile in injection molding process: data analysis and recommendations]

Objective: To investigate whether the identification of acrylonitrile, an occupational hazard factor for the industry of injection molding and plastic products, reported in literature is reasonable, and to put forward some recommendations. Methods: Professional articles published from 1990 to 2016 were searched, and an analysis was performed for the data on the determination of acrylonitrile in the industry of injection molding and plastic products from 2003 to 2016 in Longhua Center for Disease Control and Prevention of Shenzhen. Results: According to the literature, the detection rate of acrylonitrile was 10.7%, and the detection results did not exceed the limit. Conclusion: At present, acrylonitrile may not be used as a routine test item for the industry of injection molding and plastic products, in order to save manpower and material resources.

NLRC3 negatively regulates CD4+ T cells and impacts protective immunity during Mycobacterium tuberculosis infection

NLRC3, a member of the NLR family, has been reported as a negative regulator of inflammatory signaling pathways in innate immune cells. However, the direct role of NLRC3 in modulation of CD4+ T-cell responses in infectious diseases has not been studied. In the present study, we showed that NLRC3 plays an intrinsic role by suppressing the CD4+ T cell phenotype in lung and spleen, including differentiation, activation, and proliferation. NLRC3 deficiency in CD4+ T cells enhanced the protective immune response against Mycobacterium tuberculosis infection. Finally, we demonstrated that NLRC3 deficiency promoted the activation, proliferation, and cytokine production of CD4+ T cells via negatively regulating the NF-κB and MEK-ERK signaling pathways. This study reveals a critical role of NLRC3 as a direct regulator of the adaptive immune response and its protective effects on immunity during M. tuberculosis infection. Our findings also suggested that NLRC3 serves as a potential target for therapeutic intervention against tuberculosis.

Vitamin B1 Helps to Limit Mycobacterium tuberculosis Growth via Regulating Innate Immunity in a Peroxisome Proliferator-Activated Receptor-γ-Dependent Manner

It is known that vitamin B1 (VB1) has a protective effect against oxidative retinal damage induced by anti-tuberculosis drugs. However, it remains unclear whether VB1 regulates immune responses during Mycobacterium tuberculosis (MTB) infection. We report here that VB1 promotes the protective immune response to limit the survival of MTB within macrophages and in vivo through regulation of peroxisome proliferator-activated receptor γ (PPAR-γ). VB1 promotes macrophage polarization into classically activated phenotypes with strong microbicidal activity and enhanced tumor necrosis factor-α and interleukin-6 expression at least in part by promoting nuclear factor-κB signaling. In addition, VB1 increases mitochondrial respiration and lipid metabolism and PPAR-γ integrates the metabolic and inflammatory signals regulated by VB1. Using both PPAR-γ agonists and deficient mice, we demonstrate that VB1 enhances anti-MTB activities in macrophages and in vivo by down-regulating PPAR-γ activity. Our data demonstrate important functions of VB1 in regulating innate immune responses against MTB and reveal novel mechanisms by which VB1 exerts its function in macrophages.

ELTD1 Function in Hepatocellular Carcinoma is Carcinoma-Associated Fibroblast-Dependent

Introduction: EGF, latrophilin, and seven transmembrane domain containing 1 (ELTD1) constitutes an orphan G-protein-coupled receptor (GPCR) of the adhesion family. High expression of ELTD1 is correlated with favorable prognosis of hepatocellular carcinoma (HCC). After silencing ELTD1 expression, however, tumor invasiveness is drastically reduced. The underlying mechanism of this apparent contradictory phenomenon is unknown. Because adhesion GPCRs couple extracellular adhesion to intracellular signaling, as a member of this family, ELTD1 function may be related to its tumor microenvironment. We therefore investigated the interaction between ELTD1 and the HCC tumor microenvironment. Methods: ELTD1 expression was assessed by immunohistochemical analyses of tissue samples from two independent groups of 333 patients with HCC. Correlations between the ELTD1 expression and the clinicopathological values were examined. We also constructed ELTD1 overexpression and knockdown HCC cell lines and conducted a series of in vivo and in vitro ELTD1 functional assays. We further collected carcinoma associated fibroblast (CAF) culture supernatants to culture HCC cell lines and repeat the respective functional assays in comparison with the control group. Results: Clinicopathologic correlations and in vivo models indicated ELTD1 as a tumor suppressor gene, whereas in vitro experiments suggested that ELTD1 could promote malignancy in HCC cell lines. Immunohistochemical staining of the generated ELTD1 overexpression xenograft tumors demonstrated that the CAF markers vimentin and α-SMA were highly expressed compared to the control group. This suggests that ELTD1 expression is correlated to CAF distribution. In addition, culturing with CAF supernatants inhibited HCC cell proliferation and invasion rates, confirming the correlation between CAF and ELTD1. Conclusion: The results of this study indicated that ELTD1 regulation of HCC progression is CAF-dependent, suggesting that ELTD1 function is regulated by its tumor microenvironment. Further investigation is required to determine the underlying mechanisms.

Vitamin B5 Reduces Bacterial Growth via Regulating Innate Immunity and Adaptive Immunity in Mice Infected with Mycobacterium tuberculosis

The mechanisms by which vitamins regulate immunity and their effect as an adjuvant treatment for tuberculosis have gradually become very important research topics. Studies have found that vitamin B5 (VB5) can promote epithelial cells to express inflammatory cytokines. We aimed to examine the proinflammatory and antibacterial effect of VB5 in macrophages infected with Mycobacterium tuberculosis (MTB) strain H37Rv and the therapeutic potential of VB5 in vivo with tuberculosis. We investigated the activation of inflammatory signal molecules (NF-κB, AKT, JNK, ERK, and p38), the expression of two primary inflammatory cytokines (tumor necrosis factor and interleukin-6) and the bacterial burdens in H37Rv-infected macrophages stimulated with VB5 to explore the effect of VB5 on the inflammatory and antibacterial responses of macrophages. We further treated the H37Rv-infected mice with VB5 to explore VB5's promotion of the clearance of H37Rv in the lungs and the effect of VB5 on regulating the percentage of inflammatory cells. Our data showed that VB5 enhanced the phagocytosis and inflammatory response in macrophages infected with H37Rv. Oral administration of VB5 decreased the number of colony-forming units of H37Rv in lungs of mice at 1, 2, and 4 weeks after infection. In addition, VB5 regulated the percentage of macrophages and promoted CD4+ T cells to express interferon-γ and interleukin-17; however, it had no effect on the percentage of polymorphonuclear neutrophils, CD4+ and CD8+ T cells. In conclusion, VB5 significantly inhibits the growth of MTB by regulating innate immunity and adaptive immunity.

Optimal surgical strategy for hepatocellular carcinoma with portal vein tumor thrombus: a propensity score analysis

OBJECTIVES

The optimal surgical resection method for hepatocellular carcinoma (HCC) patients with portal vein tumor thrombus (PVTT) that maximizes both safety and long-term outcome has not yet been determined. The aim of this study was to compare the clinical outcomes following peeling off versus en bloc resection for PVTT.

METHODS

From 2005 to 2012, 252 patients with HCC and type I/II PVTT who underwent hepatic resection were divided into two groups according to whether they received en bloc resection (n = 113) or peeling off resection (n = 139). The clinical outcomes were compared before and after propensity score matching.

RESULTS

The propensity model matched 113 patients with en bloc resection for further analyses. After matching, overall survival (OS) and disease-free survival (DFS) rates were significantly increased in the en bloc group compared with the peeling off group (p = 0.011 and p = 0.015). A multivariate analysis indicated that en bloc resection independently improved both OS and DFS (HR = 1.471, 95% CI: 1.071-2.018, p = 0.017 and HR = 1.415, 95% CI: 1.068-1.874, P=0.016). The adverse events were not significantly different between the two groups. However, the peeling off group showed a significantly increased recurrence rate of vascular invasion compared with the en bloc group (23.9% vs. 9.7%, p = 0.005). Similar results were also demonstrated prior to the matched analysis.

CONCLUSIONS

An en bloc resection is safe and confers a survival advantage compared with a peeling off resection in HCC patients with PVTT; thus, en bloc resection should be recommended as a standard treatment for these patients when possible.

Cezanne predicts progression and adjuvant TACE response in hepatocellular carcinoma

We have previously reported that Cezanne could be a prognostic biomarker for survival in hepatocellular carcinoma (HCC) patients. However, the role of Cezanne genes in HCC cells and its response to postoperative adjuvant transcatheter arterial chemoembolization (TACE) in HCC patients remains unknown. In this study, Cezanne expression was detected in human HCC using real-time PCR, western blot and immunohistochemistry. The function of Cezanne in HCC cells was determined by Transwell invasion assays and nude mice metastasis assay. The response of Cezanne in patients who received adjuvant TACE after hepatectomy was evaluated. Functional study demonstrated that interference of Cezanne expression promoted the migration and invasion of HCC cells in vitro and boosted metastasized HCC formation in mice. Upregulation of Cezanne diminished the adhesion and migration of hepatoma cells. Further study indicated that Cezanne might inhibit invasion of HCC cells by inducing epithelial-mesenchymal transition (EMT). In addition, patients with low Cezanne expression had significant improvement in prognosis after receiving adjuvant TACE. In contrast, patients with high Cezanne expression had a poorer response to adjuvant TACE. Moreover, Cezanne status was associated with response to adjuvant TACE in patients subgroup stratified by vascular invasion, tumor size and tumor number. In conclusion, Cezanne may be a novel antioncogene that has a pivotal role in the invasion of HCC and contribute to the selection of patients who may benefit from adjuvant TACE to prevent recurrence.

IL-17 Production of Neutrophils Enhances Antibacteria Ability but Promotes Arthritis Development During Mycobacterium tuberculosis Infection

To our knowledge, no studies have examined the role of IL-17 production by neutrophils in immune defense against Mycobacterium tuberculosis (MTB) infection and the pathogenesis of rheumatoid arthritis (RA) caused by MTB infection. Here, we determined that neutrophils express IL-17 in an autocrine IL-6- and IL-23-dependent manner during MTB infection. MTB H37Rv-induced IL-6 production was dependent on the NF-κB, p38, and JNK signaling pathways; however, IL-23 production was dependent on NF-κB and EKR in neutrophils. Furthermore, we found that Toll-like receptor 2 (TLR2) and TLR4 mediated the activation of the kinases NF-κB, p38, ERK, and JNK and the production of IL-6, IL-23, and IL-17 in neutrophils infected with MTB H37Rv. Autocrine IL-17 produced by neutrophils played a vital role in inhibiting MTB H37Rv growth by mediating reactive oxygen species production and the migration of neutrophils in the early stages of infection. However, IL-17 production by neutrophils contributed to collagen-induced arthritis development during MTB infection. Our findings identify a protective mechanism against mycobacteria and the pathogenic role of MTB in arthritis development.

Vibrio vulnificus induces mTOR activation and inflammatory responses in macrophages

Vibrio vulnificus (V. vulnificus), a Gram-negative marine bacterium, can cause life-threatening primary septicemia, especially in patients with liver diseases. How V. vulnificus affects the liver and how it acts on macrophages are not well understood. In this report, we demonstrated that V. vulnificus infection causes a strong inflammatory response, marked expansion of liver-resident macrophages, and liver damage in mice. We demonstrated further that V. vulnificus activates mTOR in macrophages and inhibition of mTOR differentially regulates V. vulnificus induced inflammatory responses, suggesting the possibility of targeting mTOR as a strategy to modulate V. vulnificus induced inflammatory responses.

Cervical spinal functional magnetic resonance imaging of the spinal cord injured patient during electrical stimulation

PURPOSE

To evaluate the spatial distribution and signal intensity changes following spinal cord activation in patients with spinal cord injury.

METHODS

This study used spinal functional magnetic resonance imaging (fMRI) based on signal enhancement by extra-vascular water protons (SEEP) to assess elicited responses during subcutaneous electrical stimulation at the right elbow and right thumb in the cervical spinal cord.

RESULTS

Seven healthy volunteers and seven patients with cervical spinal cord injury (SCI) were included in this study. Significant functional activation was observed mainly in the right side of the spinal cord at the level of the C5-C6 cervical vertebra in both the axial and sagittal planes. A higher percentage of signal changes (4.66 ± 2.08 % in injured subjects vs. 2.78 ± 1.66 % in normal) and more average activation voxels (4.69 ± 2.59 in injured subjects vs. 2.56 ± 1.13 in normal subject) in axial plane at the C5-C6 cervical vertebra with a statistically significant difference. The same trends were observed in the sagittal plane with higher percentage of signal changes and more average activation voxels, though no statistically significant difference compared with the control group.

CONCLUSIONS

Spinal SEEP fMRI is a powerful noninvasive method for the study of local neuronal activation in the human spinal cord, which may be of clinical value for evaluating the effectiveness of interventions aimed at promoting recovery of function using electrical stimulation.

Essential Role of mTORC1 in Self-Renewal of Murine Alveolar Macrophages

Alveolar macrophages (AMϕ) have the capacity of local self-renewal through adult life; however, mechanisms that regulate AMϕ self-renewal remain poorly understood. We found that myeloid-specific deletion of Raptor, an essential component of the mammalian/mechanistic target of rapamycin complex (mTORC)1, resulted in a marked decrease of this population of cells accompanying altered phenotypic features and impaired phagocytosis activity. We demonstrated further that Raptor/mTORC1 deficiency did not affect AMϕ development, but compromised its proliferative activity at cell cycle entry in the steady-state as well as in the context of repopulation in irradiation chimeras. Mechanically, mTORC1 confers AMϕ optimal responsiveness to GM-CSF-induced proliferation. Thus, our results demonstrate an essential role of mTORC1 for AMϕ homeostasis by regulating proliferative renewal.

Diacylglycerol Kinases in T Cell Tolerance and Effector Function

Diacylglycerol kinases (DGKs) are a family of enzymes that regulate the relative levels of diacylglycerol (DAG) and phosphatidic acid (PA) in cells by phosphorylating DAG to produce PA. Both DAG and PA are important second messengers cascading T cell receptor (TCR) signal by recruiting multiple effector molecules, such as RasGRP1, PKCθ, and mTOR. Studies have revealed important physiological functions of DGKs in the regulation of receptor signaling and the development and activation of immune cells. In this review, we will focus on recent progresses in our understanding of two DGK isoforms, α and ζ, in CD8 T effector and memory cell differentiation, regulatory T cell development and function, and invariant NKT cell development and effector lineage differentiation.

mTOR is critical for intestinal T-cell homeostasis and resistance to Citrobacter rodentium

T-cells play an important role in promoting mucosal immunity against pathogens, but the mechanistic basis for their homeostasis in the intestine is still poorly understood. We report here that T-cell-specific deletion of mTOR results in dramatically decreased CD4 and CD8 T-cell numbers in the lamina propria of both small and large intestines under both steady-state and inflammatory conditions. These defects result in defective host resistance against a murine enteropathogen, Citrobacter rodentium, leading to the death of the animals. We further demonstrated that mTOR deficiency reduces the generation of gut-homing effector T-cells in both mesenteric lymph nodes and Peyer’s patches without obviously affecting expression of gut-homing molecules on those effector T-cells. Using mice with T-cell-specific ablation of Raptor/mTORC1 or Rictor/mTORC2, we revealed that both mTORC1 and, to a lesser extent, mTORC2 contribute to both CD4 and CD8 T-cell accumulation in the gastrointestinal (GI) tract. Additionally, mTORC1 but not mTORC2 plays an important role regulating the proliferative renewal of both CD4 and CD8 T-cells in the intestines. Our data thus reveal that mTOR is crucial for T-cell accumulation in the GI tract and for establishing local adaptive immunity against pathogens.

Critical roles of mTOR Complex 1 and 2 for T follicular helper cell differentiation and germinal center responses

T follicular helper (Tfh) cells play critical roles for germinal center responses and effective humoral immunity. We report here that mTOR in CD4 T cells is essential for Tfh differentiation. In Mtor^f/f-Cd4Cre mice, both constitutive and inducible Tfh differentiation is severely impaired, leading to defective germinal center B cell formation and antibody production. Moreover, both mTORC1 and mTORC2 contribute to Tfh and GC B cell development but may do so via distinct mechanisms. mTORC1 mainly promotes CD4 T cell proliferation to reach the cell divisions necessary for Tfh differentiation, while Rictor/mTORC2 regulates Tfh differentiation by promoting Akt activation and TCF1 expression without grossly influencing T cell proliferation. Together, our results reveal crucial but distinct roles for mTORC1 and mTORC2 in CD4 T cells during Tfh differentiation and germinal center responses.

DOI:http://dx.doi.org/10.7554/eLife.17936.001

Transarterial chemoembolization combined with sorafenib for the treatment of hepatocellular carcinoma with hepatic vein tumor thrombus

Objective

To compare the treatment outcomes of sorafenib plus transarterial chemoembolization (TACE) vs TACE alone in patients with hepatocellular carcinoma (HCC) and hepatic vein tumor thrombus (HVTT).

Methods

Twenty patients who were initially diagnosed with HCC and HVTT and received TACE combined with sorafenib during February 2009 to October 2013 were included in the study. To minimize selection bias, these patients were compared with 60 case-matched controls selected from a pool of 81 patients (in a 1:3 ratio) who received TACE alone during the same period. The primary end point was overall survival (OS). The secondary end points were time to progression, disease control rate, and adverse events.

Results

After a median follow-up period of 12.5 months (range, 1.03–44.23 months), the OS of the combined group was found to be significantly higher compared with the monotherapy group (14.9 vs 6.1 months, P=0.010). The time to progression was found to be significantly longer in the combined group (4.9 vs 2.4 months, P=0.016). Univariate and multivariate analyses revealed that the treatment allocation was an independent predictor of OS.

Conclusion

Sorafenib plus TACE was well tolerated and was more effective in treating patients with advanced HCC and HVTT. Future trials with prospective larger samples are required to validate these results.

Sustained activation of mTORC1 in macrophages increases AMPKα-dependent autophagy to maintain cellular homeostasis

Background

The mechanistic target of rapamycin complex 1 (mTORC1) is a well-conserved serine/threonine protein kinase that controls autophagy as well as many other processes such as protein synthesis, cell growth, and metabolism. The activity of mTORC1 is stringently and negatively controlled by the tuberous sclerosis proteins 1 and 2 complex (TSC1/2).

Results

In contrast to the previous studies using Tsc1 knockout mouse embryonic fibroblasts (MEF) cells, we demonstrated evidence that TSC1 deficient macrophages exhibited enhanced basal and mycobacterial infection-induced autophagy via AMPKα-dependent phosphorylation of ULK1 (Ser555). These effects were concomitant with constitutive activation of mTORC1 and can be reversed by addition of amino acids or rapamycin, and by the knockdown of the regulatory-associated protein of mTOR, Raptor. In addition, increased autophagy in TSC1 deficient macrophages resulted in suppression of inflammation during mycobacterial infection, which was reversed upon amino acid treatment of the TSC1 deficient macrophages. We further demonstrated that TSC1 conditional knockout mice infected with Mycobacterium tuberculosis, the causative agent of tuberculosis, resulted in less bacterial burden and a comparable level of inflammation when compared to wild type mice.

Conclusions

Our data revealed that sustained activation of mTORC1 due to defects in TSC1 promotes AMPKα-dependent autophagic flux to maintain cellular homeostasis.

mTORC2 in Thymic Epithelial Cells Controls Thymopoiesis and T Cell Development

Thymic epithelial cells (TECs) play important roles in T cell generation. Mechanisms that control TEC development and function are still not well defined. The mammalian or mechanistic target of rapamycin complex (mTORC)2 signals to regulate cell survival, nutrient uptake, and metabolism. We report in the present study that mice with TEC-specific ablation of Rictor, a critical and unique adaptor molecule in mTORC2, display thymic atrophy, which accompanies decreased TEC numbers in the medulla. Moreover, generation of multiple T cell lineages, including conventional TCRαβ T cells, regulatory T cells, invariant NKT cells, and TCRγδ T cells, was reduced in TEC-specific Rictor-deficient mice. Our data demonstrate that mTORC2 in TECs is important for normal thymopoiesis and efficient T cell generation.

Dominant Splice Site Mutations in PIK3R1 Cause Hyper IgM Syndrome, Lymphadenopathy and Short Stature

The purpose of this research was to use next generation sequencing to identify mutations in patients with primary immunodeficiency diseases whose pathogenic gene mutations had not been identified. Remarkably, four unrelated patients were found by next generation sequencing to have the same heterozygous mutation in an essential donor splice site of PIK3R1 (NM_181523.2:c.1425 + 1G > A) found in three prior reports. All four had the Hyper IgM syndrome, lymphadenopathy and short stature, and one also had SHORT syndrome. They were investigated with in vitro immune studies, RT-PCR, and immunoblotting studies of the mutation's effect on mTOR pathway signaling. All patients had very low percentages of memory B cells and class-switched memory B cells and reduced numbers of naïve CD4+ and CD8+ T cells. RT-PCR confirmed the presence of both an abnormal 273 base-pair (bp) size and a normal 399 bp size band in the patient and only the normal band was present in the parents. Following anti-CD40 stimulation, patient's EBV-B cells displayed higher levels of S6 phosphorylation (mTOR complex 1 dependent event), Akt phosphorylation at serine 473 (mTOR complex 2 dependent event), and Akt phosphorylation at threonine 308 (PI3K/PDK1 dependent event) than controls, suggesting elevated mTOR signaling downstream of CD40. These observations suggest that amino acids 435-474 in PIK3R1 are important for its stability and also its ability to restrain PI3K activity. Deletion of Exon 11 leads to constitutive activation of PI3K signaling. This is the first report of this mutation and immunologic abnormalities in SHORT syndrome.

mTORC1 in Thymic Epithelial Cells Is Critical for Thymopoiesis, T-Cell Generation, and Temporal Control of γδT17 Development and TCRγ/δ Recombination

Thymus is crucial for generation of a diverse repertoire of T cells essential for adaptive immunity. Although thymic epithelial cells (TECs) are crucial for thymopoiesis and T cell generation, how TEC development and function are controlled is poorly understood. We report here that mTOR complex 1 (mTORC1) in TECs plays critical roles in thymopoiesis and thymus function. Acute deletion of mTORC1 in adult mice caused severe thymic involution. TEC-specific deficiency of mTORC1 (mTORC1KO) impaired TEC maturation and function such as decreased expression of thymotropic chemokines, decreased medullary TEC to cortical TEC ratios, and altered thymic architecture, leading to severe thymic atrophy, reduced recruitment of early thymic progenitors, and impaired development of virtually all T-cell lineages. Strikingly, temporal control of IL-17-producing γδT (γδT17) cell differentiation and TCRVγ/δ recombination in fetal thymus is lost in mTORC1KO thymus, leading to elevated γδT17 differentiation and rearranging of fetal specific TCRVγ/δ in adulthood. Thus, mTORC1 is central for TEC development/function and establishment of thymic environment for proper T cell development, and modulating mTORC1 activity can be a strategy for preventing thymic involution/atrophy.

The thymus is essential for making T cells but undergoes age- or stress-associated atrophy. This study demonstrates that mTOR complex 1 in thymic epithelial cells is crucial for correct thymic architecture and the production of mature T cells.

The thymus is the primary organ for T cell generation. Abnormal thymus function profoundly affects host immunity and numerous diseases. Thymopoiesis and thymus function rely on orchestrated interaction between multiple cell types representing different origins. Among them, thymic epithelial cells (TECs) are crucial for thymus development and maintenance and T cell generation. How TEC development and function are regulated is poorly understood. The mammalian/mechanistic target of rapamycin (mTOR), a serine/threonine kinase, signals with two complexes, mTORC1 and mTOC2, to control metabolism, growth, proliferation, and survival. Using a mouse model with mTORC1 selectively ablated in TECs, we demonstrate that mTORC1 in TECs plays critical roles in thymopoiesis and thymus function. Absence of mTORC1 results in impaired TEC maturation and function, altered thymic architecture, severe thymic atrophy, and impaired development of virtually all T-cell lineages. Moreover, it also causes increased generation of IL-17–producing γδT (γδT17) cells and fetal-specific γδT subsets in adult thymus, revealing that mTORC1 in TECs is central for temporal control of γδT17 differentiation and TCRVγ/δ recombination. Our results establish mTORC1 as a central regulator for TEC development/function and for the establishment of normal thymic environment for proper T cell development. We suggest modulating mTORC1 activity as a strategy for preventing thymic involution/atrophy.

Expression of plzfa in embryo and adult of medaka Oryzias latipes

In this study, a homologous gene named plzfa was identified and characterized in medaka Oryzias latipes. Oryzias latipes plzfa was detected in all the tissues including brain, gill, muscle, liver, intestine, kidney, spleen, testis and ovary using reverse transcriptase (RT)-PCR. plzfa was detected in the oocytes of the ovary and in the spermatogonia and somitic cells of the testis by in situ hybridization. plzfa had a maternal origin with continuous and dynamic expression during embryonic development. plzfa was observed in the brain, neural rod and sensor organs including the eyes, ears and nose during embryogenesis. plzfa was also detected in the neural crest, somite, pectoral fin, intestine and skin. These results indicate that plzfa is a pleiotropic gene that may play major roles in various tissues.

TSC1 Promotes B Cell Maturation but Is Dispensable for Germinal Center Formation

Accumulating evidence indicates that the tuberous sclerosis complex 1 (TSC1), a tumor suppressor that acts by inhibiting mTOR signaling, plays an important role in the immune system. We report here that TSC1 differentially regulates mTOR complex 1 (mTORC1) and mTORC2/Akt signaling in B cells. TSC1 deficiency results in the accumulation of transitional-1 (T1) B cells and progressive losses of B cells as they mature beyond the T1 stage. Moreover, TSC1KO mice exhibit a mild defect in the serum antibody responses or rate of Ig class-switch recombination after immunization with a T-cell-dependent antigen. In contrast to a previous report, we demonstrate that both constitutive Peyer’s patch germinal centers (GCs) and immunization-induced splenic GCs are unimpaired in TSC1-deficient (TSC1KO) mice and that the ratio of GC B cells to total B cells is comparable in WT and TSC1KO mice. Together, our data demonstrate that TSC1 plays important roles for B cell development, but it is dispensable for GC formation and serum antibody responses.

iNKT cells require TSC1 for terminal maturation and effector lineage fate decisions

Terminal maturation of invariant NKT (iNKT) cells from stage 2 (CD44+NK1.1-) to stage 3 (CD44+NK1.1+) is accompanied by a functional acquisition of a predominant IFN-γ-producing (iNKT-1) phenotype; however, some cells develop into IL-17-producing iNKT (iNKT-17) cells. iNKT-17 cells are rare and restricted to a CD44+NK1.1- lineage. It is unclear how iNKT terminal maturation is regulated and what factors mediate the predominance of iNKT-1 compared with iNKT-17. The tumor suppressor tuberous sclerosis 1 (TSC1) is an important negative regulator of mTOR signaling, which regulates T cell differentiation, function, and trafficking. Here, we determined that mice lacking TSC1 exhibit a developmental block of iNKT differentiation at stage 2 and skew from a predominantly iNKT-1 population toward a predominantly iNKT-17 population, leading to enhanced airway hypersensitivity. Evaluation of purified iNKT cells revealed that TSC1 promotes T-bet, which regulates iNKT maturation, but downregulates ICOS expression in iNKT cells by inhibiting mTOR complex 1 (mTORC1). Furthermore, mice lacking T-bet exhibited both a terminal maturation defect of iNKT cells and a predominance of iNKT-17 cells, and increased ICOS expression was required for the predominance of iNKT-17 cells in the population of TSC1-deficient iNKT cells. Our data indicate that TSC1-dependent control of mTORC1 is crucial for terminal iNKT maturation and effector lineage decisions, resulting in the predominance of iNKT-1 cells.

Tuberous sclerosis 1 promotes invariant NKT cell anergy and inhibits invariant NKT cell-mediated antitumor immunity

Development of effective immune therapies for cancer patients requires better understanding of hurdles that prevent the generation of effective antitumor immune responses. Administration of α-galactosylceramide (α-GalCer) in animals enhances antitumor immunity via activation of the invariant NKT (iNKT) cells. However, repeated injections of α-GalCer result in long-term unresponsiveness or anergy of iNKT cells, severely limiting its efficacy in tumor eradication. The mechanisms leading to iNKT cell anergy remain poorly understood. We report in this study that the tuberous sclerosis 1 (TSC1), a negative regulator of mTOR signaling, plays a crucial role in iNKT cell anergy. Deficiency of TSC1 in iNKT cells results in resistance to α-GalCer-induced anergy, manifested by increased expansion of and cytokine production by iNKT cells in response to secondary Ag stimulation. It is correlated with impaired upregulation of programmed death-1, Egr2, and Grail. Moreover, TSC1-deficient iNKT cells display enhanced antitumor immunity in a melanoma lung metastasis model. Our data suggest targeting TSC1/2 as a strategy for boosting antitumor immune therapy.

The role of diacylglycerol kinase ζ and phosphatidic acid in the mechanical activation of mammalian target of rapamycin (mTOR) signaling and skeletal muscle hypertrophy

The activation of mTOR signaling is essential for mechanically induced changes in skeletal muscle mass, and previous studies have suggested that mechanical stimuli activate mTOR (mammalian target of rapamycin) signaling through a phospholipase D (PLD)-dependent increase in the concentration of phosphatidic acid (PA). Consistent with this conclusion, we obtained evidence which further suggests that mechanical stimuli utilize PA as a direct upstream activator of mTOR signaling. Unexpectedly though, we found that the activation of PLD is not necessary for the mechanically induced increases in PA or mTOR signaling. Motivated by this observation, we performed experiments that were aimed at identifying the enzyme(s) that promotes the increase in PA. These experiments revealed that mechanical stimulation increases the concentration of diacylglycerol (DAG) and the activity of DAG kinases (DGKs) in membranous structures. Furthermore, using knock-out mice, we determined that the ζ isoform of DGK (DGKζ) is necessary for the mechanically induced increase in PA. We also determined that DGKζ significantly contributes to the mechanical activation of mTOR signaling, and this is likely driven by an enhanced binding of PA to mTOR. Last, we found that the overexpression of DGKζ is sufficient to induce muscle fiber hypertrophy through an mTOR-dependent mechanism, and this event requires DGKζ kinase activity (i.e. the synthesis of PA). Combined, these results indicate that DGKζ, but not PLD, plays an important role in mechanically induced increases in PA and mTOR signaling. Furthermore, this study suggests that DGKζ could be a fundamental component of the mechanism(s) through which mechanical stimuli regulate skeletal muscle mass.

MicroRNA-34a enhances T cell activation by targeting diacylglycerol kinase ζ

The engagement of the T cell receptor (TCR) induces the generation of diacylglycerol (DAG), an important second messenger activating both the Ras/Erk and PKCθ/NFκB pathways. DAG kinases (DGKs) participate in the metabolism of DAG by converting it to phosphatidic acid. DGKζ has been demonstrated to be able to inhibit DAG signaling following TCR engagement. Deficiency of DGKζ increases the sensitivity of T cells to TCR stimulation, resulting in enhanced T cell activation ex vivo and in vivo. However, the mechanisms that control DGKζ expression are poorly understood. Here we demonstrate that DGKζ mRNA is a direct target of a cellular microRNA miR-34a. The DGKζ transcript is decreased, whereas the primary miR-34a is upregulated upon TCR stimulation. Ectopic miR-34a expression suppresses DGKζ protein expression through the seed match binding to both the 3' untranslated region and coding region of DGKζ mRNA, leading to increased ERK1/2 phosphorylation and surface expression of the T cell activation marker CD69 following TCR cross-linking. In contrast, overexpression of a miR-34a competitive inhibitor increases DGKζ expression and suppresses TCR-mediated T cell activation. Together, our data demonstrate that miR-34a is a negative regulator for DGKζ and may play an important role in regulating T cell activation.

Diacylglycerol kinase ζ limits B cell antigen receptor-dependent activation of ERK signaling to inhibit early antibody responses

Signaling downstream of the B cell antigen receptor (BCR) is tightly regulated to enable cells to gauge the strength and duration of antigen-receptor interactions and to respond appropriately. We investigated whether metabolism of the second messenger diacylglycerol (DAG) by members of the family of DAG kinases (DGKs) played a role in modulating the magnitude of signaling by DAG downstream of the BCR. In the absence of DGKζ, the threshold for BCR signaling, measured as activation of the Ras-extracellular signal-regulated kinase (ERK) pathway, was markedly reduced in mature follicular B cells, which resulted in enhanced responses to antigen in vitro and in vivo. Inhibition of DAG signaling by DGKζ limited the number of antibody-secreting cells that were generated early in response to T cell-independent type 2 antigens, as well as to T cell-dependent antigens. Furthermore, the effect of loss of DGKζ closely resembled the effect of increasing the affinity of the BCR for antigen during the T cell-dependent antibody response. These results suggest that the magnitude of DAG signaling is important for translating the affinity of the BCR for antigen into the amount of antibody produced during the early stages of an immune response.