Poly(ADP-ribose) polymerase 9 mediates early protection against Mycobacterium tuberculosis infection by regulating type I IFN production

The ADP ribosyltransferases (PARPs 1-17) regulate diverse cellular processes, including DNA damage repair. PARPs are classified on the basis of their ability to catalyze poly-ADP-ribosylation (PARylation) or mono-ADP-ribosylation (MARylation). Although PARP9 mRNA expression is significantly increased in progressive tuberculosis (TB) in humans, its participation in host immunity to TB is unknown. Here, we show that PARP9 mRNA encoding the MARylating PARP9 enzyme was upregulated during TB in humans and mice and provide evidence of a critical modulatory role for PARP9 in DNA damage, cyclic GMP-AMP synthase (cGAS) expression, and type I IFN production during TB. Thus, Parp9-deficient mice were susceptible to Mycobacterium tuberculosis infection and exhibited increased TB disease, cGAS and 2'3'-cyclic GMP-AMP (cGAMP) expression, and type I IFN production, along with upregulation of complement and coagulation pathways. Enhanced M. tuberculosis susceptibility is type I IFN dependent, as blockade of IFN α receptor (IFNAR) signaling reversed the enhanced susceptibility of Parp9-/- mice. Thus, in sharp contrast to PARP9 enhancement of type I IFN production in viral infections, this member of the MAR family plays a protective role by limiting type I IFN responses during TB.

CXCR2 expression during melanoma tumorigenesis controls transcriptional programs that facilitate tumor growth

BACKGROUND

Though the CXCR2 chemokine receptor is known to play a key role in cancer growth and response to therapy, a direct link between expression of CXCR2 in tumor progenitor cells during induction of tumorigenesis has not been established.

METHODS

To characterize the role of CXCR2 during melanoma tumorigenesis, we generated tamoxifen-inducible tyrosinase-promoter driven BrafV600E/Pten-/-/Cxcr2-/- and NRasQ61R/INK4a-/-/Cxcr2-/- melanoma models. In addition, the effects of a CXCR1/CXCR2 antagonist, SX-682, on melanoma tumorigenesis were evaluated in BrafV600E/Pten-/- and NRasQ61R/INK4a-/- mice and in melanoma cell lines. Potential mechanisms by which Cxcr2 affects melanoma tumorigenesis in these murine models were explored using RNAseq, mMCP-counter, ChIPseq, and qRT-PCR; flow cytometry, and reverse phosphoprotein analysis (RPPA).

RESULTS

Genetic loss of Cxcr2 or pharmacological inhibition of CXCR1/CXCR2 during melanoma tumor induction resulted in key changes in gene expression that reduced tumor incidence/growth and increased anti-tumor immunity. Interestingly, after Cxcr2 ablation, Tfcp2l1, a key tumor suppressive transcription factor, was the only gene significantly induced with a log2 fold-change greater than 2 in these three different melanoma models.

CONCLUSIONS

Here, we provide novel mechanistic insight revealing how loss of Cxcr2 expression/activity in melanoma tumor progenitor cells results in reduced tumor burden and creation of an anti-tumor immune microenvironment. This mechanism entails an increase in expression of the tumor suppressive transcription factor, Tfcp2l1, along with alteration in the expression of genes involved in growth regulation, tumor suppression, stemness, differentiation, and immune modulation. These gene expression changes are coincident with reduction in the activation of key growth regulatory pathways, including AKT and mTOR.

CXCR2 expression during melanoma tumorigenesis controls transcriptional programs that facilitate tumor growth

Background

Though the CXCR2 chemokine receptor is known to play a key role in cancer growth and response to therapy, a direct link between expression of CXCR2 in tumor progenitor cells during induction of tumorigenesis has not been established.

Methods

To characterize the role of CXCR2 during melanoma tumorigenesis, we generated tamoxifen-inducible tyrosinase-promoter driven Braf ^V600E /Pten ^-/- /Cxcr2 ^-/- and NRas ^Q61R /INK4a ^-/- /Cxcr2 ^-/- melanoma models. In addition, the effects of a CXCR1/CXCR2 antagonist, SX-682, on melanoma tumorigenesis were evaluated in Braf ^V600E /Pten ^-/- and NRas ^Q61R /INK4a ^-/- mice and in melanoma cell lines. Potential mechanisms by which Cxcr2 affects melanoma tumorigenesis in these murine models were explored using RNAseq, mMCP-counter, ChIPseq, and qRT-PCR; flow cytometry, and reverse phosphoprotein analysis (RPPA).

Results

Genetic loss of Cxcr2 or pharmacological inhibition of CXCR1/CXCR2 during melanoma tumor induction resulted in key changes in gene expression that reduced tumor incidence/growth and increased anti-tumor immunity. Interestingly, after Cxcr2 ablation, Tfcp2l1 , a key tumor suppressive transcription factor, was the only gene significantly induced with a log ₂ fold-change greater than 2 in these three different melanoma models.

Conclusions

Here, we provide novel mechanistic insight revealing how loss of Cxcr2 expression/activity in melanoma tumor progenitor cells results in reduced tumor burden and creation of an anti-tumor immune microenvironment. This mechanism entails an increase in expression of the tumor suppressive transcription factor, Tfcp2l1, along with alteration in the expression of genes involved in growth regulation, tumor suppression, stemness, differentiation, and immune modulation. These gene expression changes are coincident with reduction in the activation of key growth regulatory pathways, including AKT and mTOR.

Selective inhibition of mTORC1 in tumor vessels increases antitumor immunity

A tumor blood vessel is a key regulator of tissue perfusion, immune cell trafficking, cancer metastasis, and therapeutic responsiveness. mTORC1 is a signaling node downstream of multiple angiogenic factors in the endothelium. However, mTORC1 inhibitors have limited efficacy in most solid tumors, in part due to inhibition of immune function at high doses used in oncology patients and compensatory PI3K signaling triggered by mTORC1 inhibition in tumor cells. Here we show that low-dose RAD001/everolimus, an mTORC1 inhibitor, selectively targets mTORC1 signaling in endothelial cells (ECs) without affecting tumor cells or immune cells, resulting in tumor vessel normalization and increased antitumor immunity. Notably, this phenotype was recapitulated upon targeted inducible gene ablation of the mTORC1 component Raptor in tumor ECs (RaptorECKO). Tumors grown in RaptorECKO mice displayed a robust increase in tumor-infiltrating lymphocytes due to GM-CSF-mediated activation of CD103+ dendritic cells and displayed decreased tumor growth and metastasis. GM-CSF neutralization restored tumor growth and metastasis, as did T cell depletion. Importantly, analyses of human tumor data sets support our animal studies. Collectively, these findings demonstrate that endothelial mTORC1 is an actionable target for tumor vessel normalization, which could be leveraged to enhance antitumor immune therapies.

Abstract B58: The role of EphA2 receptor tyrosine kinase in antitumor immunity mediated through programmed death ligand 2 (PD-L2) in non-small cell lung cancer (NSCLC)

Despite the advent of targeted therapies and breakthrough immunotherapies, lung cancer remains the number one cause of cancer-related death. Immune checkpoint inhibitors against PD-1 and PD-L1 induce remarkable and durable responses in a fraction of NSCLC patients, but most fail to respond or develop intolerable autoimmune-related toxicities. Additionally, the current standard of using PD-L1 expression alone as a biomarker is not strongly predictive of patient response and reveals the challenges that clinicians face when the understanding of the underlying biology lags behind clinical implementation.

EphA2 receptor tyrosine kinase is implicated in many solid tumors, including NSCLC, as well as inflammatory processes. Blockade of EphA2 induces apoptosis in NSCLC cells and increases survival in mouse models of NSCLC, demonstrating that EphA2 is a viable target for therapeutic intervention in NSCLC. Here, we examine how EphA2 in NSCLC cancer cells affects the PD-1 and PD-L1/2 checkpoint signaling axis in the tumor microenvironment. Preliminary studies suggest that EphA2 regulates the expression of PD-L2, but not PD-L1, in normal epithelium, as well as NSCLC cell lines. Knockdown of EphA2 by siRNA in BEAS-2B human bronchial epithelial cells shows decreased surface PD-L2 expression by flow cytometry. Additionally, PD-L2 expression is induced in human NSCLC cell lines by cytokine stimulation, specifically IFNg and IL-4. Knockdown of EphA2 in a subset of KRAS mutant human NSCLC cell lines after cytokine stimulation decreased PD-L2 expression. Analysis of NSCLC surgical specimens and survival data demonstrate that higher PD-L2 expression correlates with worse prognosis.

Despite PD-L2’s known role in immune tolerance, its impact on the tumor microenvironment is greatly understudied compared to PD-L1. Thus, further elucidation of EphA2s role in regulating PD-1 and PD-L2 interactions in functional assays and in in vivo mouse models will further our understanding of PD-1 and PD-L1/PD-L2 biology in the tumor immune microenvironment and will be critical for predicting the effects of immune checkpoint inhibitors.

Citation Format: Eileen F. Shiuan, Shan Wang, Ariel Raybuck, Mark Boothby, Jin Chen. The role of EphA2 receptor tyrosine kinase in antitumor immunity mediated through programmed death ligand 2 (PD-L2) in non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr B58.

PARP14 Controls the Nuclear Accumulation of a Subset of Type I IFN-Inducible Proteins

The enzymes of the poly-ADP-ribose polymerase (PARP) superfamily control many relevant cellular processes, but a precise understanding of their activities in different physiological or disease contexts is largely incomplete. We found that transcription of several Parp genes was dynamically regulated upon murine macrophage activation by endotoxin. PARP14 was strongly induced by several inflammatory stimuli and translocated into the nucleus of stimulated cells. Quantitative mass spectrometry analysis showed that PARP14 bound to a group of IFN-stimulated gene (ISG)-encoded proteins, most with an unknown function, and it was required for their nuclear accumulation. Moreover, PARP14 depletion attenuated transcription of primary antiviral response genes regulated by the IFN regulatory transcription factor 3, including Ifnb1, thus reducing IFN-β production and activation of ISGs involved in the secondary antiviral response. In agreement with the above-mentioned data, PARP14 hindered Salmonella typhimurium proliferation in murine macrophages. Overall, these data hint at a role of PARP14 in the control of antimicrobial responses and specifically in nuclear activities of a subgroup of ISG-encoded proteins.

Metabolic Regulation of the Immune Humoral Response

Productive humoral responses require that naive B cells and their differentiated progeny move among distinct micro-environments. In this review, we discuss how studies are beginning to address the nature of these niches as well as the interplay between cellular signaling, metabolic programming, and adaptation to the locale. Recent work adds evidence to the expectation that B cells at distinct stages of development or functional subsets are influenced by the altered profiles of nutrients and metabolic by-products that distinguish these sites. Moreover, emerging findings reveal a cross-talk among the external milieu, signal transduction pathways, and transcription factors that direct B cell fate in the periphery.

PI3K Inhibition Reduces Mammary Tumor Growth and Facilitates Antitumor Immunity and Anti-PD1 Responses

Purpose: Metastatic breast cancers continue to elude current therapeutic strategies, including those utilizing PI3K inhibitors. Given the prominent role of PI3Kα,β in tumor growth and PI3Kγ,δ in immune cell function, we sought to determine whether PI3K inhibition altered antitumor immunity.Experimental Design: The effect of PI3K inhibition on tumor growth, metastasis, and antitumor immune response was characterized in mouse models utilizing orthotopic implants of 4T1 or PyMT mammary tumors into syngeneic or PI3Kγ-null mice, and patient-derived breast cancer xenografts in humanized mice. Tumor-infiltrating leukocytes were characterized by IHC and FACS analysis in BKM120 (30 mg/kg, every day) or vehicle-treated mice and PI3Kγ^null versus PI3Kγ^WT mice. On the basis of the finding that PI3K inhibition resulted in a more inflammatory tumor leukocyte infiltrate, the therapeutic efficacy of BKM120 (30 mg/kg, every day) and anti-PD1 (100 μg, twice weekly) was evaluated in PyMT tumor-bearing mice.Results: Our findings show that PI3K activity facilitates tumor growth and surprisingly restrains tumor immune surveillance. These activities could be partially suppressed by BKM120 or by genetic deletion of PI3Kγ in the host. The antitumor effect of PI3Kγ loss in host, but not tumor, was partially reversed by CD8⁺ T-cell depletion. Treatment with therapeutic doses of both BKM120 and antibody to PD-1 resulted in consistent inhibition of tumor growth compared with either agent alone.Conclusions: PI3K inhibition slows tumor growth, enhances antitumor immunity, and heightens susceptibility to immune checkpoint inhibitors. We propose that combining PI3K inhibition with anti-PD1 may be a viable therapeutic approach for triple-negative breast cancer. Clin Cancer Res; 23(13); 3371-84. ©2016 AACR.

PARP9 and PARP14 cross-regulate macrophage activation via STAT1 ADP-ribosylation

Despite the global impact of macrophage activation in vascular disease, the underlying mechanisms remain obscure. Here we show, with global proteomic analysis of macrophage cell lines treated with either IFNγ or IL-4, that PARP9 and PARP14 regulate macrophage activation. In primary macrophages, PARP9 and PARP14 have opposing roles in macrophage activation. PARP14 silencing induces pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells, whereas it suppresses anti-inflammatory gene expression and STAT6 phosphorylation in M(IL-4) cells. PARP9 silencing suppresses pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells. PARP14 induces ADP-ribosylation of STAT1, which is suppressed by PARP9. Mutations at these ADP-ribosylation sites lead to increased phosphorylation. Network analysis links PARP9-PARP14 with human coronary artery disease. PARP14 deficiency in haematopoietic cells accelerates the development and inflammatory burden of acute and chronic arterial lesions in mice. These findings suggest that PARP9 and PARP14 cross-regulate macrophage activation.

Is telephone follow-up as good as traditional clinic follow-up in achieving the proposed national outcome standards for chlamydia management?

A retrospective review of 400 cases of genital chlamydia managed with a traditional clinic follow-up was compared to 400 cases with a telephone follow-up appointment. We satisfactorily treated more patients with the telephone follow-up appointment than with a traditional clinic follow-up (204 [51%] vs 121 [30%]; P <0.0001). We also satisfactorily treated more partners with the telephone follow-up system than a traditional clinic appointment system (0.57 vs 0.45 contacts per case; P =0.0006). The introduction of the telephone follow-up appointment system in the clinic increased the number of patients and contacts of patients successfully managed for genital chlamydial infection. Our findings should lead to increased research and adoption of different methods of follow-up and help develop proper outcome standards.

Class-biased regulation of humoral immunity and mTORC1 inhibition by physiological hypoxia

B lymphocytes activated by cognate antigen (Ag) proliferate, are selected for affinity maturation, undergo antibody (Ab) class switching dependent on the cytosine deaminase AID, and yield major forms of memory via germinal center (GC) reactions. Although metabolic programming has emerged as a means of mediating or initiating changes in immunity, nothing is known as to the metabolic landscape in lymphoid organs. Here we show that B lymphocytes in GC are hypoxic, and that low oxygen alters B cell Ab response as well as metabolic programming. In addition to increased B cell death, restricted oxygen concentrations impaired Ab class switching by reducing expression of AID and suppressing the pro-inflammatory IgG2c Ab isotype. Prolyl hydroxyl dioxygenases (PHD) and von Hippel-Lindau (VHL) are central to regulation of hypoxia-induced factors (HIF) in hypoxic responses. B cell-intrinsic deficiency of VHL attenuated Ag-specific IgG2c, and decreased levels of Ag-specific GC, early memory B cells, and Ab responses. Hypoxia and VHL deficiency each also inhibited activity of mTORC1 in a manner dependent on HIF proteins. Genetic limitation of mTORC1 in B cells reduced their clonal expansion, AID expression, and IgG2c Ab responses. Collectively, these results provide evidence that GC reactions are sites of physiologic hypoxia that in turn regulates vital functions of B cells through interruption of program that maintains mTORC1 activity. We propose that this restriction of oxygen regulates the balance of fate choices made by GC B cells, and that pathophysiological states that alter oxygen homeostasis may moderate the pro-inflammatory component of humoral immunity.

Signaling in T cells - is anything the m(a)TOR with the picture(s)?

The excitement surrounding checkpoint inhibitors in the treatment of patients with cancer exemplifies a triumph of the long-term value of investing in basic science and fundamental questions of T-cell signaling. The pharmaceutical future actively embraces ways of making more patients’ cancers responsive to these inhibitors. Such a process will be aided by elucidation of signaling and regulation. With thousands of articles spread across almost 30 years, this commentary can touch only on portions of the canonical picture of T-cell signaling and provide a few parables from work on mammalian (or mechanistic) target of rapamycin (mTOR) pathways as they link to early and later phases of lymphocyte activation. The piece will turn a critical eye to some issues with models about these pathways in T cells. Many of the best insights lie in the future despite all that is uncovered already, but a contention is that further therapeutic successes will be fostered by dealing with disparities among findings and attention to the temporal, spatial, and stochastic aspects of T-cell responses. Finally, thoughts on some (though not all) items urgently needed for future progress will be mooted.

TLR4 genotype and environmental LPS mediate RSV bronchiolitis through Th2 polarization

While 30%-70% of RSV-infected infants develop bronchiolitis, 2% require hospitalization. It is not clear why disease severity differs among healthy, full-term infants; however, virus titers, inflammation, and Th2 bias are proposed explanations. While TLR4 is associated with these disease phenotypes, the role of this receptor in respiratory syncytial virus (RSV) pathogenesis is controversial. Here, we evaluated the interaction between TLR4 and environmental factors in RSV disease and defined the immune mediators associated with severe illness. Two independent populations of infants with RSV bronchiolitis revealed that the severity of RSV infection is determined by the TLR4 genotype of the individual and by environmental exposure to LPS. RSV-infected infants with severe disease exhibited a high GATA3/T-bet ratio, which manifested as a high IL-4/IFN-γ ratio in respiratory secretions. The IL-4/IFN-γ ratio present in infants with severe RSV is indicative of Th2 polarization. Murine models of RSV infection confirmed that LPS exposure, Tlr4 genotype, and Th2 polarization influence disease phenotypes. Together, the results of this study identify environmental and genetic factors that influence RSV pathogenesis and reveal that a high IL-4/IFN-γ ratio is associated with severe disease. Moreover, these molecules should be explored as potential targets for therapeutic intervention.

Myeloid IKKβ promotes antitumor immunity by modulating CCL11 and the innate immune response

Myeloid cells are capable of promoting or eradicating tumor cells and the nodal functions that contribute to their different roles are still obscure. Here, we show that mice with myeloid-specific genetic loss of the NF-κB pathway regulatory kinase IKKβ exhibit more rapid growth of cutaneous and lung melanoma tumors. In a BRAF(V600E/PTEN(-/-)) allograft model, IKKβ loss in macrophages reduced recruitment of myeloid cells into the tumor, lowered expression of MHC class II molecules, and enhanced production of the chemokine CCL11, thereby negatively regulating dendritic-cell maturation. Elevated serum and tissue levels of CCL11 mediated suppression of dendritic-cell differentiation/maturation within the tumor microenvironment, skewing it toward a Th2 immune response and impairing CD8(+) T cell-mediated tumor cell lysis. Depleting macrophages or CD8(+) T cells in mice with wild-type IKKβ myeloid cells enhanced tumor growth, where the myeloid cell response was used to mediate antitumor immunity against melanoma tumors (with less dependency on a CD8(+) T-cell response). In contrast, myeloid cells deficient in IKKβ were compromised in tumor cell lysis, based on their reduced ability to phagocytize and digest tumor cells. Thus, mice with continuous IKKβ signaling in myeloid-lineage cells (IKKβ(CA)) exhibited enhanced antitumor immunity and reduced melanoma outgrowth. Collectively, our results illuminate new mechanisms through which NF-κB signaling in myeloid cells promotes innate tumor surveillance.

microRNA-mediated regulation of mTOR complex components facilitates discrimination between activation and anergy in CD4 T cells

Using Dicer-deficient CD4 T cells, Marcais et al. show that microRNAs regulate the expression of mTOR components that are needed to discriminate between activating and anergy-inducing stimuli.

T cell receptor (TCR) signals can elicit full activation with acquisition of effector functions or a state of anergy. Here, we ask whether microRNAs affect the interpretation of TCR signaling. We find that Dicer-deficient CD4 T cells fail to correctly discriminate between activating and anergy-inducing stimuli and produce IL-2 in the absence of co-stimulation. Excess IL-2 production by Dicer-deficient CD4 T cells was sufficient to override anergy induction in WT T cells and to restore inducible Foxp3 expression in Il2-deficient CD4 T cells. Phosphorylation of Akt on S473 and of S6 ribosomal protein was increased and sustained in Dicer-deficient CD4 T cells, indicating elevated mTOR activity. The mTOR components Mtor and Rictor were posttranscriptionally deregulated, and the microRNAs Let-7 and miR-16 targeted the Mtor and Rictor mRNAs. Remarkably, returning Mtor and Rictor to normal levels by deleting one allele of Mtor and one allele of Rictor was sufficient to reduce Akt S473 phosphorylation and to reduce co-stimulation–independent IL-2 production in Dicer-deficient CD4 T cells. These results show that microRNAs regulate the expression of mTOR components in T cells, and that this regulation is critical for the modulation of mTOR activity. Hence, microRNAs contribute to the discrimination between T cell activation and anergy.

B cell-intrinsic and -extrinsic regulation of antibody responses by PARP14, an intracellular (ADP-ribosyl)transferase

The capacity to achieve sufficient concentrations of Ag-specific Ab of the appropriate isotypes is a critical component of immunity that requires efficient differentiation and interactions of Ag-specific B and Th cells along with dendritic cells. Numerous bacterial toxins catalyze mono(ADP-ribosyl)ation of mammalian proteins to influence cell physiology and adaptive immunity. However, little is known about biological functions of intracellular mammalian mono(ADP-ribosyl)transferases, such as any ability to regulate Ab responses. poly-(ADP-ribose) polymerase 14 (PARP14), an intracellular protein highly expressed in lymphoid cells, binds to STAT6 and encodes a catalytic domain with mammalian mono(ADP-ribosyl)transferase activity. In this article, we show that recall IgA as well as the STAT6-dependent IgE Ab responses are impaired in PARP14-deficient mice. Whereas PARP14 regulation of IgE involved a B cell-intrinsic process, the predominant impact on IgA was B cell extrinsic. Of note, PARP14 deficiency reduced the levels of Th17 cells and CD103⁺ DCs, which are implicated in IgA regulation. PARP14 enhanced the expression of RORα, Runx1, and Smad3 after T cell activation, and, importantly, its catalytic activity of PARP14 promoted Th17 differentiation. Collectively, the findings show that PARP14 influences the class distribution, affinity repertoire, and recall capacity of Ab responses in mice, as well as provide direct evidence of the requirement for protein mono-ADP-ribosylation in Th cell differentiation.

STAT4 and T-bet are required for the plasticity of IFN-γ expression across Th2 ontogeny and influence changes in Ifng promoter DNA methylation

CD4(+) T cells developing toward a Th2 fate express IL-4, IL-5, and IL-13 while inhibiting production of cytokines associated with other Th types, such as the Th1 cytokine IFN- γ. IL-4-producing Th2 effector cells give rise to a long-lived memory population committed to reactivation of the Th2 cytokine gene expression program. However, reactivation of these effector-derived cells under Th1-skewing conditions leads to production of IFN-γ along with IL-4 in the same cell. We now show that this flexibility ("plasticity") of cytokine expression is preceded by a loss of the repressive DNA methylation of the Ifng promoter acquired during Th2 polarization yet requires STAT4 along with T-box expressed in T cells. Surprisingly, loss of either STAT4 or T-box expressed in T cells increased Ifng promoter CpG methylation in both effector and memory Th2 cells. Taken together, our data suggest a model in which the expression of IFN-γ by Th2-derived memory cells involves attenuation of epigenetic repression in memory Th2 cells, combined with Th1-polarizing signals after their recall activation.

The Goldilocks effect

Modest overexpression of an epigenetic regulatory protein in a developmental disorder alters T helper cell differentiation and causes immune defects.

B cell intrinsic and extrinsic roles of ADP-ribosyltransferase, PARP14 in regulation of IgA and IgE responses (P1078)

Immunological memory, including both persistent and recall antibody (Ab) responses, enables more efficient and effective protection against infection, but key molecular mechanisms regulating emergence and persistence of memory B cells and plasma cells remain unclear. Poly-ADP-Ribose Polymerase14 (PARP14) is highly expressed in B cells and identified as a Stat6-interacting protein with intrinsic mono-ADP-ribosyltransferase (mART) activity. Although there are 17 PARP family members, the physiological function of most PARPs are not known well. Here we show that recall IgA and IgE production are impaired in PARP14-deficient mice. Further analysis revealed that, although PARP14 regulation of IgE involves B cell intrinsic function, IgA regulation by PARP14 was predominantly B cell extrinsic. Of note, PARP14 regulates the levels of CD103+ dendritic cells and T helper 17 (Th17) cells which might influence IgA generation in B cells. Moreover, PARP14 regulates the expression of RORα, Runx1 and Smad3 during Th17 differentiation, and mART activity of PARP plays a critical role in Th17 differentiation. Collectively, these results shed new light on differential mechanisms of Ig regulation, provide evidence that an endogenous mono ADP-ribosyltransferase regulates recall Ab production, and may have important implications for a new therapeutic target.

Enhanced pro-inflammatory profile and Th17 alloresponse by targeting mTORC2 in DC (P2138)

Mammalian target of rapamycin (mTOR) is an important integrative kinase that regulates immune cell function. mTOR functions in two independent complexes: mTOR complex (mTORC) 1 and 2. The immunosuppressant Rapamycin inhibits mTORC1 but not mTORC2. Our aim was to study the immune regulatory role and underlying mechanistic properties of mTORC2 in DC. We generated a conditional mTORC2 knockout, targeting Rictor. Bone marrow cells were obtained from KO and WT B6 controls, and DC propagated in the presence of IL-4 and GM-CSF, with or without LPS. The phenotype, cytokine production, STAT3 activation and ability of DC to induce allogeneic T cell proliferation were evaluated, and also the responder T cell phenotype and cytokine production. DC differentiation was not affected, while DC yield was slightly reduced in mTORC2-deficient BM cultures compared with WT controls. DC lacking mTORC2 activity displayed similar levels of MHC and co-stimulatory molecules, but diminished B7-H1 expression, increased levels of IL-12p40, diminished STAT3 activation and higher T cell stimulatory ability following LPS stimulation, compared with WT. Staining of allogeneic T cells stimulated by Rictor-KO DC revealed more CD4+IL-17+ cells than those stimulated with WT DC. These novel data indicate that DC lacking mTORC2 activity exhibit an enhanced pro-inflammatory profile with ability to promote Th17 responses. Thus, targeting mTORC2 provides new insight into molecular regulation of DC function.

Rapamycin-resistant mTORC1 restrains dendritic cell B7-H1 expression that requires IL-1β to enhance regulatory T cell induction (P1349)

Introduction: The mammalian Target of Rapamycin (mTOR) is a central regulator of dendritic cell (DC) function that performs the catalytic activity of mTOR complex (mTORC)1 and 2. mTORC2 functions independently from mTORC1 and is resistant to inhibition by rapamycin (RAPA); however, mTORC1 has both RAPA-sensitive and -resistant outputs. Our goal was to ascertain the role of RAPA-resistant mTOR in DC. Methods: WT C57BL/6 or B7-H1-/- bone marrow-derived DC were generated with the addition of RAPA or ATP-competitive mTOR inhibitor, which blocks all mTOR signaling. DC lacking rictor, an mTORC2-specific subunit, were generated from conditional rictor KO mice. DC induction of regulatory T cells (Treg) was determined in MLR, using BALB/c CD4+CD25- T cell responders. Results and Conclusion: RAPA and mTORC2 deletion reduced DC B7-H1 expression, but ATP-competitive mTOR inhibitors enhanced B7-H1 expression. Augmented B7-H1 expression was blocked by STAT3 inhibition and correlated with reduced expression of the STAT3 negative regulator, SOCS3. DC exposed to ATP-competitive mTOR inhibitors increased Treg induction, which was dependent on DC B7-H1. IL-1β neutralization additionally reduced Treg induction by B7-H1-/- ATP-competitive mTOR inhibitor-exposed DC, suggesting that IL-1β and B7-H1 act additively to promote Treg induction by these DC. These findings establish a RAPA-resistant mTORC1 pathway that acts through SOCS3 and STAT3 to regulate DC B7-H1 expression and Treg induction.

INK4a/ARF [corrected] inactivation with activation of the NF-κB/IL-6 pathway is sufficient to drive the development and growth of angiosarcoma

Although human angiosarcoma has been associated frequently with mutational inactivation of the tumor suppressor gene Ink4a/Arf, the underlying mechanisms have not been delineated. Here we report that malignant angiosarcoma is associated with high levels of RelA/NF-κB and IL-6 in contrast to normal vessels or benign hemagiomas. Studies of Ink4a/Arf deficient mice not only recapitulate genetic traits observed in human angiosarcoma, but also unveil a possible therapeutic link comprised of the NF-kB/IL-6/Stat3 signaling axis. In Ink4a/Arf(-/-) cells, NF-κB controlled Stat3 signaling by transcriptionally controlling the expression of IL-6, gp130, and Jak2. Further, IL-6 mediated Stat3 signaling through the sIL-6R. Inhibition of Ikkβ solely in myeloid cells was insufficient to block angiosarcoma development; in contrast, systemic inhibition of Ikkβ, IL-6, or Stat3 markedly inhibited angiosarcoma growth. Our findings offer clinical implications for targeting the NF-kB/IL-6/STAT3 pathway as a rational strategy to treat angiosarcoma.

Effects of cancer-associated EPHA3 mutations on lung cancer

BACKGROUND

Cancer genome sequencing efforts recently identified EPHA3, which encodes the EPHA3 receptor tyrosine kinase, as one of the most frequently mutated genes in lung cancer. Although receptor tyrosine kinase mutations often drive oncogenic conversion and tumorigenesis, the oncogenic potential of the EPHA3 mutations in lung cancer remains unknown.

METHODS

We used immunoprecipitation, western blotting, and kinase assays to determine the activity and signaling of mutant EPHA3 receptors. A mutation-associated gene signature was generated from one large dataset, mapped to another training dataset with survival information, and tested in a third independent dataset. EPHA3 expression levels were determined by quantitative reverse transcription-polymerase chain reaction in paired normal-tumor clinical specimens and by immunohistochemistry in human lung cancer tissue microarrays. We assessed tumor growth in vivo using A549 and H1299 human lung carcinoma cell xenografts in mice (n = 7-8 mice per group). Tumor cell proliferation was measured by bromodeoxyuridine incorporation and apoptosis by multiple assays. All P values are from two-sided tests.

RESULTS

At least two cancer-associated EPHA3 somatic mutations functioned as dominant inhibitors of the normal (wild type) EPHA3 protein. An EPHA3 mutation-associated gene signature that was associated with poor patient survival was identified. Moreover, EPHA3 gene copy numbers and/or expression levels were decreased in tumors from large cohorts of patients with lung cancer (eg, the gene was deleted in 157 of 371 [42%] primary lung adenocarcinomas). Reexpression of wild-type EPHA3 in human lung cancer lines increased apoptosis by suppression of AKT activation in vitro and inhibited the growth of tumor xenografts (eg, for H1299 cells, mean tumor volume with wild-type EPHA3 = 437.4 mm(3) vs control = 774.7 mm(3), P < .001). Tumor-suppressive effects of wild-type EPHA3 could be overridden in trans by dominant negative EPHA3 somatic mutations discovered in patients with lung cancer.

CONCLUSION

Cancer-associated EPHA3 mutations attenuate the tumor-suppressive effects of normal EPHA3 in lung cancer.

Vital roles of mTOR complex 2 in Notch-driven thymocyte differentiation and leukemia

Rictor is essential in Notch-driven T-ALL pathogenesis.

Notch plays critical roles in both cell fate decisions and tumorigenesis. Notch receptor engagement initiates signaling cascades that include a phosphatidylinositol 3-kinase/target of rapamycin (TOR) pathway. Mammalian TOR (mTOR) participates in two distinct biochemical complexes, mTORC1 and mTORC2, and the relationship between mTORC2 and physiological outcomes dependent on Notch signaling is unknown. In this study, we report contributions of mTORC2 to thymic T-cell acute lymphoblastic leukemia (T-ALL) driven by Notch. Conditional deletion of Rictor, an essential component of mTORC2, impaired Notch-driven proliferation and differentiation of pre-T cells. Furthermore, NF-κB activity depended on the integrity of mTORC2 in thymocytes. Active Akt restored NF-κB activation, a normal rate of proliferation, and differentiation of Rictor-deficient pre-T cells. Strikingly, mTORC2 depletion lowered CCR7 expression in thymocytes and leukemic cells, accompanied by decreased tissue invasion and delayed mortality in T-ALL driven by Notch. Collectively, these findings reveal roles for mTORC2 in promoting thymic T cell development and T-ALL and indicate that mTORC2 is crucial for Notch signaling to regulate Akt and NF-κB.

NIH Portfolio Allocation, Lemmings, and the Silent Spring: A Time-Capsule Commentary & Its Update

With the release of the US President's proposed budget for the Federal Fiscal year (FY) 2013, to start October 1, 2012, we've spun yet again into the mad vortex of an appropriation season. Fundamental re-thinks of how biological and medical research are prioritized and funded are urgently needed, but sadly appear to be unlikely unless the research and advocacy communities push harder and in a more unified manner. Early in the Obama presidency and the NIH Directorship of Dr Francis Collins, the FASEB Office of Public Affairs performed an analysis of trends in funding of R01 and other Research Project Grants and shared that with the Director and his office. Using the FASEB analysis, whose numbers drew on NIH data, an independent commentary (below) was submitted to (but not published in) Science. With the analysis a few years old, this older viewpoint is followed by updates that touch on how the trends have fared since early 2010 and comment on other aspects of the ongoing cull in biomedical research. In particular, data on some of the growth areas that continue to prosper at the expense of the ever-declining direct support for R01 science are discussed.

Progress in the function and regulation of ADP-Ribosylation

Adenosine 5'-diphosphate (ADP)-ribosylation is a protein posttranslational modification that is catalyzed by ADP-ribosyltransferases (ARTs), using nicotinamide adenine dinucleotide (NAD(+)) as a substrate. Mono-ribosylation can be extended into polymers of ADP-ribose (PAR). Poly(ADP-ribosyl)polymerase (PARP) 1, the best-characterized cellular enzyme catalyzing this process, is the prototypical member of a family of mono- and poly(ADP-ribosyl)transferases. The physiological consequences of ADP-ribosylation are inadequately understood. PARP2010, the 18th International Conference on ADP-Ribosylation, attracted scientists from all over the world to Zurich, Switzerland. Highlights from this meeting include promising clinical trials with PARP inhibitors and new insights into cell, structural, and developmental biology of ARTs and the (glyco)hydrolase proteins that catalyze de-ADP-ribosylation of mono- or poly-ADP-ribosylated proteins. Moreover, potential links to the NAD-dependent sirtuin family were explored on the basis of a shared dependence on cellular NAD(+) concentrations and the relationship of ADP-ribosylation with intermediary metabolism and cellular energetics.

PARP-14 mediates B cell memory response through the regulation of energy metabolism and gene transcription (61.5)

Immunological memory, including both persistent and recall antibody (Ab) responses, enables more efficient and effective protection against recurrent or chronic infection. Although many basic features of memory responses are understood, key molecular mechanisms regulating emergence and persistence of memory B cells and plasma cells remain unknown. Recent evidence suggests that the regulation of energy metabolism might mediate memory T cell differentiation and function. PARP-14, a Stat6-interacting protein is highly expressed in lymphoid organs, influences B cell subset ratios as well as the initial IgA response to antigen, and has intrinsic ADP-ribosyltransferase activity. We now show that PARP-14 is essential for the regulation of energy metabolism in B cells and has been significant role in the increased Ag-specific Ab levels that follow booster immunization. Investigation of the mechanism(s) revealed that PARP-14 mediates at least in part to the formation of long-lived plasma cell formation and regulates IL-4 induction of PRDM1 (Blimp-1), a master regulator of plasma cell differentiation. These results reveal a novel function of a mammalian ADP-ribosyltransferase in memory of B lineage cells and may shed a light on a new target for vaccine development.

mTOR complex 2 mediates Notch signaling in thymocyte and T-cell leukemia development (64.8)

Mammalian target of rapamycin (mTOR) is an important component of the PI3-kinase (PI3K) pathway that regulates cell growth and proliferation. PI3K signaling cascades can be initiated by activation of Notch, a critical regulator for T lineage commitment and leukemia development. Here we show that mTOR complex 2 (mTORC2) is functionally vital as a downstream target of Notch in thymocytes and T-cell acute lymphoblastic leukemia (T-ALL). Conditional deletion of rictor, an essential component of mTORC2, results in impaired proliferation and differentiation of pre-T cells driven by Notch ligation. Moreover, mTORC2 is a primary kinase for Akt S473 and enhances Akt activity in thymocytes. Furthermore, mTORC2 regulates NF-κB activity, such that constitutively active Akt can restore nuclear NF-κB levels in the rictor-depleted pre-T cells, as well as normalizing Notch-initiated proliferation and differentiation. Strikingly, interruption of mTORC2 significantly delays T-ALL induced by Notch1 activating mutation and suppresses infiltration of leukemic cells into the non-lymphoid organs. Our study provides evidence of a key role of mTORC2 in relaying Notch signaling in thymocyte development, and reveals that mTORC2 promotes Notch-driven leukemia progression.

Mammalian target of rapamycin protein complex 2 regulates differentiation of Th1 and Th2 cell subsets via distinct signaling pathways

Many functions of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) have been defined, but relatively little is known about the biology of an alternative mTOR complex, mTORC2. We showed that conditional deletion of rictor, an essential subunit of mTORC2, impaired differentiation into T helper 1 (Th1) and Th2 cells without diversion into FoxP3(+) status or substantial effect on Th17 cell differentiation. mTORC2 promoted phosphorylation of protein kinase B (PKB, or Akt) and PKC, Akt activity, and nuclear NF-kappaB transcription factors in response to T cell activation. Complementation with active Akt restored only T-bet transcription factor expression and Th1 cell differentiation, whereas activated PKC-theta reverted only GATA3 transcription factor and the Th2 cell defect of mTORC2 mutant cells. Collectively, the data uncover vital mTOR-PKC and mTOR-Akt connections in T cell differentiation and reveal distinct pathways by which mTORC2 regulates development of Th1 and Th2 cell subsets.

A comparison of treatment outcomes for moxifloxacin versus ofloxacin/metronidazole for first-line treatment of uncomplicated non-gonococcal pelvic inflammatory disease

Large randomized controlled trials support the efficacy of moxifloxacin for the treatment of uncomplicated pelvic inflammatory disease (PID). This study compares the clinical outcome and tolerability of treatment with moxifloxacin 400 mg once a day or ofloxacin 400 mg plus metronidazole 400 mg both twice daily in patients diagnosed with PID. A retrospective case-notes review was performed on patients diagnosed clinically with PID before and after local guidelines were changed to recommend moxifloxacin as first-line treatment for uncomplicated PID. Before the guidelines changed, 114/134 (85%) patients received the recommended first-line therapy versus 206/257 (80%) after the change, P = 0.3. There was no difference in the clinical outcomes between the two groups; significant improvement/resolved 77% versus 70%; marginal improvement 3% versus 11%; no change/worse 20% versus 18%, P = 0.14. Moxifloxacin is confirmed to be an effective alternative to ofloxacin/metronidazole for the treatment of PID in a large urban genitourinary clinic setting.

The calculus of integrating differentiation: timing control of T-bet

In this issue of Immunity, Schulz et al. (2009) use mathematical modeling to elucidate a signaling network controlling Ifng gene expression, thereby showing the importance of an Interleukin-12-dependent, Interferon-gamma-independent second phase of inducing the transcription factor T-bet.

PARP-14 mediates IL-4-enhanced metabolic function and survival of B cells (97.4)

IL-4 is survival factor for lymphocytes and other hematopoietic cells. Whether there are mechanisms of pro-survival signaling induced by IL-4 apart from PI3K-Akt activation is not fully clear. Our laboratory identified PARP-14, a poly-ADP-ribose polymerase subfamily member, as a Stat6-interacting protein. PARP-14 is highly expressed in lymphoid organs, influences B cell subset ratios as well as the IgA response to antigen, and has intrinsic ADP-ribosyltransferase activity. ADP-ribosyltransferases and PARPs catalyze mono- and poly-ADP-ribosylation, transferring ADP from NAD+ to target proteins. ADP-ribosylation is a post-translational modification used by bacterial exotoxins to impact signal transduction, or, in the case of the mammalian PARP-1, to influence gene transcription and DNA repair or trigger apoptosis. Almost nothing is known about biological roles or mechanisms of action of other mammalian PARPs. We now show that PARP-14 is essential for full survival signaling despite normal Akt activation in B cells. Investigation of the mechanism(s) revealed that PARP-14 mediates IL-4 induction of gene products known to promote cell survival, and also metabolic functions of B cells. Moreover, intervention that restored glycolytic activity in IL-4-treated B cells also rescued pro-survival signaling. These results reveal a novel link to metabolic regulation via a mammalian ADP-ribosyltransferase.

Mammalian target of rapamycin complex 2 regulates helper T cell differentiation and function (47.31)

Mammalian target of rapamycin (mTOR) is involved in cellular processes such as survival and proliferation. Regulation of the original rapamycin-sensitive complex, mTORC1, in signaling downstream from Akt is well defined. However, physiological roles in lymphoid cells of an alternative mTOR complex, mTORC2, are unknown. Using conditional deletion of rictor, an essential subunit of mTORC2, we recently uncovered a rate-limiting role of mTORC2 in T cell development and Akt activation. We now show that mTORC2 regulates helper T cell development and function by a pathway that is either Akt-dependent or largely independent of Akt, depending on the direction of differentiation. Specifically deleting rictor late in T cell ontogeny impaired T cell help to Ab class switching for both Th1- and Th2-regulated isotypes. mTORC2 relayed signaling of helper T cell help differentiation into both Th1 and Th2 effector cells, and proliferation distinct from pro-survival effects. Strikingly, a constitutive active Akt was sufficient to restore normal Th1, but not Th2 differentiation. Overall, our data indicate that mTORC2 plays fundamental roles in cellular differentiation while orchestrating differential signaling relays.

Preferences for partner notification method: variation in responses between respondents as index patients and contacts

There have been very few studies focusing on what form of communication patients would find acceptable from a clinic. This study looks at the differences in preferences for various partner notification methods when the respondents were index patients compared with when they had to be contacted because a partner had a sexually transmitted infection (STI). There were 2544 respondents. When the clinic had to notify partners, respondents were more likely to report the method as good when a partner had an STI and they were being contacted compared with when the respondents had an infection and the partner was being contacted. The opposite was true for patient referral partner notification. Therefore, there are variations in the preferences of respondents for partner notification method, which depend on whether they see themselves as index patients or contacts.

Collaborator of Stat6 (CoaSt6)-associated poly(ADP-ribose) polymerase activity modulates Stat6-dependent gene transcription

The transcription factor Stat6 plays a critical role in interleukin-4-dependent gene activation. To mediate this function, Stat6 recruits canonical transcriptional co-activators including the histone acetyl transferases CREB-binding protein and NCoA-1 and other proteins such as a p100 co-factor. However, much remains unknown regarding the constituents of Stat6 enhancer complexes, and the exact molecular events that modulate Stat6-dependent gene activation are not fully understood. Recently, we identified a novel co-factor, CoaSt6 (collaborator of Stat6), which associates with Stat6 and enhances its transcriptional activity. Sequence homologies place CoaSt6 in a superfamily of poly(ADP-ribosyl)polymerase (PARP)-like proteins. We have demonstrated here that PARP enzymatic activity is associated with CoaSt6, and this function of CoaSt6 can append ADP-ribose to itself and p100. Further, we show that a catalytically inactive mutant of CoaSt6 was unable to enhance Stat6-mediated transcription of a test promoter. Consistent with these findings, chemical inhibition of PARP activity blocked interleukin-4-dependent transcription from target promoters in vivo. Taken together, we have identified a CoaSt6-associated PARP activity and provided evidence for a role of poly(ADP ribosyl)ation in Stat-mediated transcriptional responses involving a novel PARP.

Patient preferences for partner notification

OBJECTIVE

To identify patient preferences for notification of sexual contacts when a sexually transmitted infection (STI) is diagnosed.

METHODS

A questionnaire survey of 2544 patients attending three large genitourinary clinics at Derby, Birmingham, and Coventry in the United Kingdom.

RESULTS

The median age of the respondents was 24 with 1474 (57.9%) women, 1835 (72.1%) white, 1826 (71.8%) single. The most favoured method of partner notification was patient referral, which was rated a "good" method by 65.8% when they had to be contacted because a sexual partner has an STI. Notifying contacts by letter as a method of provider partner notification is more acceptable than phoning, text messaging, or email. Respondents with access to mobile telephones, private emails, and private letters were more likely to rate a method of partner notification using that mode of communication as "good" compared to those without. With provider referral methods of partner notification respondents preferred to receive a letter, email, or text message asking them to contact the clinic rather than a letter, email or text message informing them that they may have an STI.

CONCLUSION

Most respondents think that being informed directly by a partner is the best method of being notified of the risk of an STI. Some of the newer methods may not be acceptable to all but a significant minority of respondents prefer these methods of partner notification. The wording of letters, emails, or text messages when used for partner notification has an influence on the acceptability of the method and may influence success of the partner notification method. Services should be flexible enough to utilise the patients' preferred method of partner notification.

T helper type 1-specific Brg1 recruitment and remodeling of nucleosomes positioned at the IFN-gamma promoter are Stat4 dependent

Transcriptional competence of the interferon-gamma (IFN-gamma) locus is enhanced as Th1 effectors develop from naive CD4 T lymphocytes; conversely, this gene is repressed during Th2 differentiation. We now show that the Switch (Swi)-sucrose nonfermenter (SNF) component Brahma-related gene 1 (Brg1) is recruited, and positioned nucleosomes are remodeled, in a Th1-specific manner that is dependent on the transcription factor Stat4 and calcineurin phosphatase activity. Interference with specific components of mammalian Swi-SNF complexes decreased CD4 T cell differentiation into IFN-gamma-positive Th1 cells. These findings reveal a collaborative mechanism of IFN-gamma gene regulation during Th1 differentiation and suggest that a Th1-specific chromatin structure is created by early recruitment of Swi-SNF complexes and nucleosome remodeling dependent on Stat4 and calcineurin activation.

Oxidant stress modulates murine allergic airway responses

The allergic inflammation occurring in asthma is believed to be accompanied by the production of free radicals. To investigate the role of free radicals and the cells affected we turned to a murine model of allergic inflammation produced by sensitization to ovalbumin with subsequent aerosol challenge. We examined oxidant stress by measuring and localizing the sensitive and specific marker of lipid peroxidation, the F2-isoprostanes. F2-isoprostanes in whole lung increased from 0.30 +/- 0.08 ng/lung at baseline to a peak of 0.061 +/- 0.09 ng/lung on the ninth day of daily aerosol allergen challenge. Increased immunoreactivity to 15-F2t-IsoP (8-iso-PGF2alpha) or to isoketal protein adducts was found in epithelial cells 24 h after the first aerosol challenge and at 5 days in macrophages. Collagen surrounding airways and blood vessels, and airway and vascular smooth muscle, also exhibited increased immunoreactivity after ovalbumin challenge. Dietary vitamin E restriction in conjunction with allergic inflammation led to increased whole lung F2-isoprostanes while supplemental vitamin E suppressed their formation. Similar changes in immunoreactivity to F2-isoprostanes were seen. Airway responsiveness to methacholine was also increased by vitamin E depletion and decreased slightly by supplementation with the antioxidant. Our findings indicate that allergic airway inflammation in mice is associated with an increase in oxidant stress, which is most striking in airway epithelial cells and macrophages. Oxidant stress plays a role in the production of airway responsiveness.