Inhibition of the BTK-IDO-mTOR axis promotes differentiation of monocyte-lineage dendritic cells and enhances anti-tumor T cell immunity

Monocytic-lineage inflammatory Ly6c+CD103+ dendritic cells (DCs) promote antitumor immunity, but these DCs are infrequent in tumors, even upon chemotherapy. Here, we examined how targeting pathways that inhibit the differentiation of inflammatory myeloid cells affect antitumor immunity. Pharmacologic inhibition of Bruton's tyrosine kinase (BTK) and the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) or deletion of Btk or Ido1 allowed robust differentiation of inflammatory Ly6c+CD103+ DCs during chemotherapy, promoting antitumor T cell responses and inhibiting tumor growth. Immature Ly6c+c-kit+ precursor cells had epigenetic profiles similar to conventional DC precursors; deletion of Btk or Ido1 promoted differentiation of these cells. Mechanistically, a BTK-IDO axis inhibited a tryptophan-sensitive differentiation pathway driven by GATOR2 and mTORC1, and disruption of the GATOR2 in monocyte-lineage precursors prevented differentiation into inflammatory DCs in vivo. IDO-expressing DCs and monocytic cells were present across a range of human tumors. Thus, a BTK-IDO axis represses differentiation of inflammatory DCs during chemotherapy, with implications for targeted therapies.

Generalised surface waves at the boundary of piezo-poroelastic medium with arbitrary anisotropy

This study considers the propagation of surface waves along all directions on the plane boundary of piezo-poroelastic half-space with arbitrary anisotropy. This generalised propagation is characterized through an anisotropic phase velocity, which should ensure the decay of wave-field with depth into the medium. A linear homogeneous system of six equations with complex coefficients governs the existence and propagation of surface waves in the considered medium. The real phase velocity of surface waves lies implicit in a complex determinantal equation, which ensures a non-trivial solution to the system of equations. Through a specific transformation, the system of complex equations is modified to yield a real secular equation, with phase velocity being the only unknown. This equation can always be solved numerically for phase velocity of surface wave along any direction on the plane boundary of anisotropic piezo-poroelastic medium. The phase velocity has been used further to calculate the components of energy flux at the boundary. Horizontal components of energy flux define the group velocity and ray direction for the surface wave. A numerical example is solved to analyse the phase/group velocity curves at the boundary of the medium.

The alarmin cytokine IL-1a drives a feedback-amplification loop between dying tumor cells and inflammatory monocyte-lineage dendritic cells

Successful immunotherapy must transform the normally suppressive tumor microenvironment into a pro-inflammatory, immunogenic milieu. We show that this critical transformation depends on a previously unrecognized initiating signal delivered by the damage-associated “alarmin” cytokine interleukin-1a (IL-1a). Initially, tumor-intrinsic IL-1a was mobilized from dying tumor cells. This drove rapid local differentiation of a population of monocyte-lineage inflammatory dendritic cells (DCs). We have previously described these inflammation-inducible myeloid DCs in tumors (Sharma et. al, Immunity 48:91–106, 2018), where they serve as key antigen-presenting cells during multiple forms of immunotherapy and chemo-immuno-therapy. Once these inflammatory DCs were elicited by tumor-derived IL-1a, they rapidly re-activated anergic/unresponsive tumor-associated CD8+ T cells. Then DCs and T cells together produced reciprocal host-derived IL-1a, thus completing a potent self-amplifying feedback loop. If this IL-1a-driven feedback-amplification loop was disrupted – either by silencing IL-1a in the tumor cells; or ablating IL-1a in the host cells; or disrupting the IL-1-receptor on the inflammatory dendritic cells – then anti-tumor immune activation was lost across multiple forms of immunotherapy and chemotherapy. To restore the ability to initiate immune activation, the only cells that needed to respond to IL-1a were the specific population of inflammatory monocyte-lineage DCs.

Multidrug Therapy for HIV Infection: Dynamics of Immune System

A mathematical model of the dynamics of the immune system is considered to illustrate the effect of its response to HIV infection, i.e. on viral growth and on T-cell dynamics. The specific immune response is measured by the levels of cytotoxic lymphocytes in a human body. The existence and stability analyses are performed for infected steady state and uninfected steady state. In order to keep infection under control, roles of drug therapies are analyzed in the presence of efficient immune response. Numerical simulations are computed and exhibited to illustrate the support of the immune system to drug therapies, so as to ensure the decay of infection and to maintain the level of healthy cells.

Sexual selection drives the evolution of male wing interference patterns

The seemingly transparent wings of many insects have recently been found to display unexpected structural coloration. These structural colours (wing interference patterns: WIPs) may be involved in species recognition and mate choice, yet little is known about the evolutionary processes that shape them. Furthermore, to date investigations of WIPs have not fully considered how they are actually perceived by the viewers' colour vision. Here, we use multispectral digital imaging and a model of Drosophila vision to compare WIPs of male and female Drosophila simulans from replicate populations forced to evolve with or without sexual selection for 68 generations. We show that WIPs modelled in Drosophila vision evolve in response to sexual selection and provide evidence that WIPs correlate with male sexual attractiveness. These findings add a new element to the otherwise well-described Drosophila courtship display and confirm that wing colours evolve through sexual selection.

Monocyte-lineage dendritic cell (DC) precursors are pre-positioned in normal lymph nodes and rapidly differentiate into Batf3+ cross-presenting APCs during inflammation

We have shown (Immunity 48:91–106, 2018) that a subset of murine monocytic precursor cells are plastic, and can up-regulate a Batf3-driven differentiation program resembling classical cDC1 cells. The resulting inflammatory DCs are important in tumor immunity, but it has been unclear whether they played a role in normal immune responses. We now identify the precursor cells for these inflammatory DCs as a population of Ly6c+ ckit+ c− fms+ CD11b-neg cells. These are constitutively present in all resting LNs (comprising up to half of the Ly6c+ cells). In response to a standard vaccination model of cross-presented antigen (whole OVA protein plus CpG adjuvant in IFA), the precursor cells rapidly up-regulated Batf3 and differentiated into CD103+ IRF8+ DCs. Just as in tumors, maturation was dependent on intracellular p53 signaling in the precursor cells. Targeted disruption of p53 (LysMcre/p53-KO) had no effect on the number of precursors, but abrogated their ability to mature into Batf3+ DCs. In KO mice, the loss of this single monocytic DC population entirely abrogated the ability to create an inflammatory milieu in the vaccine-draining LN, and abolished cross-presentation of protein antigen to T cells. In contrast, direct presentation (soluble siinfekl peptide) remained intact. We hypothesize that the ability of monocyte-lineage cells to differentiate into Batf3+ APCs during inflammation is an important component of the normal cross-presentation process.

Treg Destabilization and Reprogramming: Implications for Cancer Immunotherapy

Regulatory T cells (Tregs) are an important contributor to the immunosuppressive tumor microenvironment. To date, however, they have been difficult to target for therapy. One emerging new aspect of Treg biology is their apparent functional instability in the face of certain acute proinflammatory signals such as IL6 and IFNγ. Under the right conditions, these signals can cause a rapid loss of suppressor activity and reprogramming of the Tregs into a proinflammatory phenotype. In this review, we propose the hypothesis that this phenotypic modulation does not reflect infidelity to the Treg lineage, but rather represents a natural, physiologic response of Tregs during beneficial inflammation. In tumors, however, this inflammation-induced Treg destabilization is actively opposed by dominant stabilizing factors such as indoleamine 2,3-dioxygenase and the PTEN phosphatase pathway in Tregs. Under such conditions, tumor-associated Tregs remain highly suppressive and inhibit cross-presentation of tumor antigens released by dying tumor cells. Interrupting these Treg stabilizing pathways can render tumor-associated Tregs sensitive to rapid destabilization during immunotherapy, or during the wave of cell death following chemotherapy or radiation, thus enhancing antitumor immune responses. Understanding the emerging pathways of Treg stabilization and destabilization may reveal new molecular targets for therapy. Cancer Res; 78(18); 5191-9. ©2018 AACR.

Activation of p53 in Immature Myeloid Precursor Cells Controls Differentiation into Ly6c+CD103+ Monocytic Antigen-Presenting Cells in Tumors

CD103⁺ dendritic cells are critical for cross-presentation of tumor antigens. Here we have shown that during immunotherapy, large numbers of cells expressing CD103 arose in murine tumors via direct differentiation of Ly6c⁺ monocytic precursors. These Ly6c⁺CD103⁺ cells could derive from bone-marrow monocytic progenitors (cMoPs) or from peripheral cells present within the myeloid-derived suppressor cell (MDSC) population. Differentiation was controlled by inflammation-induced activation of the transcription factor p53, which drove upregulation of Batf3 and acquisition of the Ly6c⁺CD103⁺ phenotype. Mice with a targeted deletion of p53 in myeloid cells selectively lost the Ly6c⁺CD103⁺ population and became unable to respond to multiple forms of immunotherapy and immunogenic chemotherapy. Conversely, increasing p53 expression using a p53-agonist drug caused a sustained increase in Ly6c⁺CD103⁺ cells in tumors during immunotherapy, which markedly enhanced the efficacy and duration of response. Thus, p53-driven differentiation of Ly6c⁺CD103⁺ monocytic cells represents a potent and previously unrecognized target for immunotherapy.

Activation of host p53 enhances anti-tumor immunity by driving differentiation of immunogenic myeloid DCs in tumors, while simultaneously protecting against collateral autoimmunity against shared self-tumor antigens

During immunotherapy, we show that large numbers of immunogenic CD103+ DCs can arise in murine tumors via direct differentiation myeloid-lineage (Ly6c+ monocytic) precursors. These “dual-phenotype” Ly6c+CD103+ DCs differentiate from a precursor population of monocytic myeloid-derived suppressor cells (MDSCs) in tumors. Differentiation was controlled by inflammation-induced activation of the transcription factor p53 in MDSCs. Targeted deletion of myeloid p53 selectively ablated the Ly6c+CD103+ DC population, which resulted in abrogation of all response to multiple forms of tumor immunotherapy. Pharmacologically elevating the level of p53 expression in host cells, by administering the p53-agonist (MDM2-inhibitor) drug nutlin-3a, caused a sustained increase in Ly6c+CD103+ DCs in tumors during immunotherapy, and markedly enhanced anti-tumor immunity. Conversely, however, when a nominal tumor antigen (OVA) was also shared by a critical host tissue (Rip-mOVA mice), elevation of host p53 using nutlin-3a was potent immunosuppressive and protective against lethal autoimmunity outside of the tumor, while still driving enhanced immunity – against the same antigen – within the tumor itself. Thus, p53-agonist drugs may represent a novel class immunotherapy agents, with high discrimination between tumor-associated antigens and collateral autoimmunity.

The Drosophila simulans Y chromosome interacts with the autosomes to influence male fitness

The Y chromosome should degenerate because it cannot recombine. However, male-limited transmission increases selection efficiency for male-benefit alleles on the Y, and therefore, Y chromosomes should contribute significantly to variation in male fitness. This means that although the Drosophila Y chromosome is small and gene-poor, Y-linked genes are vital for male fertility in Drosophila melanogaster and the Y chromosome has large male fitness effects. It is unclear whether the same pattern is seen in the closely related Drosophila simulans. We backcrossed Y chromosomes from three geographic locations into five genetic backgrounds and found strong Y and genetic background effects on male fertility. There was a significant Y-background interaction, indicating substantial epistasis between the Y and autosomal genes affecting male fertility. This supports accumulating evidence that interactions between the Y chromosome and the autosomes are key determinants of male fitness.

IDO, PTEN-expressing Tregs and control of antigen-presentation in the murine tumor microenvironment

The tumor microenvironment is profoundly immunosuppressive. This creates a major barrier for attempts to combine immunotherapy with conventional chemotherapy or radiation, because the tumor antigens released by these cytotoxic agents are not cross-presented in an immunogenic fashion. In this Focused Research Review, we focus on mouse preclinical studies exploring the role of immunosuppressive Tregs expressing the PTEN lipid phosphatase, and the links between PTEN+ Tregs and the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO). IDO has received attention because it can be expressed by a variety of human tumor types in vivo, but IDO can also be induced in host immune cells of both humans and mice in response to inflammation, infection or dying (apoptotic) cells. Mechanistically, IDO and PTEN+ Tregs are closely connected, with IDO causing activation of the PTEN pathway in Tregs. Genetic ablation or pharmacologic inhibition of PTEN in mouse Tregs destabilizes their suppressive phenotype, and this prevents transplantable and autochthonous tumors from creating their normal immunosuppressive microenvironment. Genetic ablation of either IDO or PTEN+ Tregs in mice results in a fundamental defect in the ability to maintain tolerance to antigens associated with apoptotic cells, including dying tumor cells. Consistent with this, pharmacologic inhibitors of either pathway show synergy when combined with cytotoxic agents such as chemotherapy or radiation. Thus, we propose that IDO and PTEN+ Tregs represent closely linked checkpoints that can influence the choice between immune activation versus tolerance to dying tumor cells.

Constrained evolution of the sex comb in Drosophila simulans

Male fitness is dependent on sexual traits that influence mate acquisition (precopulatory sexual selection) and paternity (post-copulatory sexual selection), and although many studies have documented the form of selection in one or the other of these arenas, fewer have done it for both. Nonetheless, it appears that the dominant form of sexual selection is directional, although theoretically, populations should converge on peaks in the fitness surface, where selection is stabilizing. Many factors, however, can prevent populations from reaching adaptive peaks. Genetic constraints can be important if they prevent the development of highest fitness phenotypes, as can the direction of selection if it reverses across episodes of selection. In this study, we examine the evidence that these processes influence the evolution of the multivariate sex comb morphology of male Drosophila simulans. To do this, we conduct a quantitative genetic study together with a multivariate selection analysis to infer how the genetic architecture and selection interact. We find abundant genetic variance and covariance in elements of the sex comb. However, there was little evidence for directional selection in either arena. Significant nonlinear selection was detected prior to copulation when males were mated to nonvirgin females, and post-copulation during sperm offence (again with males mated to nonvirgins). Thus, contrary to our predictions, the evolution of the D. simulans sex comb is limited neither by genetic constraints nor by antagonistic selection between pre- and post-copulatory arenas, but nonlinear selection on the multivariate phenotype may prevent sex combs from evolving to reach some fitness maximizing optima.

Fisher's sons' effect in sexual selection: absent, intermittent or just low experimental power?

The Fisherian sexual selection paradigm has been called the null model of sexual selection. At its heart is the expectation of a genetic correlation (r_G ) between female preference and male trait. However, recent meta-analysis has shown estimated correlations are often extremely weak and not statistically significant. We show here that systematic failure of studies to reject the null hypothesis that r_G  = 0 is almost certainly due to the low power of most experimental designs used. We provide an easy way to assess experimental power a priori and suggest that current data make it difficult to definitively test a key component of the Fisher effect.

Local adaptation of a bacterium is as important as its presence in structuring a natural microbial community

Local adaptation of a species can affect community composition, yet the importance of local adaptation compared with species presence per se is unknown. Here we determine how a compost bacterial community exposed to elevated temperature changes over 2 months as a result of the presence of a focal bacterium, Pseudomonas fluorescens SBW25, that had been pre-adapted or not to the compost for 48 days. The effect of local adaptation on community composition is as great as the effect of species presence per se, with these results robust to the presence of an additional strong selection pressure: an SBW25-specific virus. These findings suggest that evolution occurring over ecological time scales can be a key driver of the structure of natural microbial communities, particularly in situations where some species have an evolutionary head start following large perturbations, such as exposure to antibiotics or crop planting and harvesting.

Though both the presence and traits of a species can influence the dynamics of its ecological community, the effects of these factors are difficult to disentangle. Here, Gómez et al. demonstrate in a microbial mesocosm that local adaptation of a focal species can influence the community as much as the presence of the focal species per se.

Pre and Post-copulatory Selection Favor Similar Genital Phenotypes in the Male Broad Horned Beetle

Sexual selection can operate before and after copulation and the same or different trait(s) can be targeted during these episodes of selection. The direction and form of sexual selection imposed on characters prior to mating has been relatively well described, but the same is not true after copulation. In general, when male–male competition and female choice favor the same traits then there is the expectation of reinforcing selection on male sexual traits that improve competitiveness before and after copulation. However, when male–male competition overrides pre-copulatory choice then the opposite could be true. With respect to studies of selection on genitalia there is good evidence that male genital morphology influences mating and fertilization success. However, whether genital morphology affects reproductive success in more than one context (i.e., mating versus fertilization success) is largely unknown. Here we use multivariate analysis to estimate linear and nonlinear selection on male body size and genital morphology in the flour beetle Gnatocerus cornutus, simulated in a non-competitive (i.e., monogamous) setting. This analysis estimates the form of selection on multiple traits and typically, linear (directional) selection is easiest to detect, while nonlinear selection is more complex and can be stabilizing, disruptive, or correlational. We find that mating generates stabilizing selection on male body size and genitalia, and fertilization causes a blend of directional and stabilizing selection. Differences in the form of selection across these bouts of selection result from a significant alteration of nonlinear selection on body size and a marginally significant difference in nonlinear selection on a component of genital shape. This suggests that both bouts of selection favor similar genital phenotypes, whereas the strong stabilizing selection imposed on male body size during mate acquisition is weak during fertilization.

The PTEN pathway in Tregs is a critical driver of the suppressive tumor microenvironment

The tumor microenvironment is profoundly immunosuppressive. We show that multiple tumor types create intratumoral immune suppression driven by a specialized form of regulatory T cell (Treg) activation dependent on the PTEN (phosphatase and tensin homolog) lipid phosphatase. PTEN acted to stabilize Tregs in tumors, preventing them from reprogramming into inflammatory effector cells. In mice with a Treg-specific deletion of PTEN, tumors grew slowly, were inflamed, and could not create an immunosuppressive tumor microenvironment. In normal mice, exposure to apoptotic tumor cells rapidly elicited PTEN-expressing Tregs, and PTEN-deficient mice were unable to maintain tolerance to apoptotic cells. In wild-type mice with large established tumors, pharmacologic inhibition of PTEN after chemotherapy or immunotherapy profoundly reconfigured the tumor microenvironment, changing it from a suppressive to an inflammatory milieu, and tumors underwent rapid regression. Thus, the immunosuppressive milieu in tumors must be actively maintained, and tumors become susceptible to immune attack if the PTEN pathway in Tregs is disrupted.

Potential for combination of dipeptidyl peptidase-4 inhibitors and sodium-glucose co-transporter-2 inhibitors for the treatment of type 2 diabetes

In individuals with advanced type 2 diabetes (T2DM), combination therapy is often unavoidable to maintain glycaemic control. Currently metformin is considered the first line of defence, but many patients experience gastrointestinal adverse events, necessitating an alternative treatment approach. Established therapeutic classes, such as sulphonylureas and thiazolidinediones, have some properties undesirable in individuals with T2DM, such as hypoglycaemia risk, weight gain and fluid retention, highlighting the need for newer agents with more favourable safety profiles that can be combined and used at all stages of T2DM. New treatment strategies have focused on both dipeptidyl peptidase (DPP)-4 inhibitors, which improve hyperglycaemia by stimulating insulin secretion in a glucose-dependent fashion and suppressing glucagon secretion, and sodium-glucose co-transporter-2 (SGLT2) inhibitors, which reduce renal glucose reabsorption and induce urinary glucose excretion, thereby lowering plasma glucose. The potential complimentary mechanism of action and good tolerance profile of these two classes of agents make them attractive treatment options for combination therapy with any of the existing glucose-lowering agents, including insulin. Together, the DPP-4 and SGLT2 inhibitors fulfill a need for treatments with mechanisms of action that can be used in combination with a low risk of adverse events, such as hypoglycaemia or weight gain.

Environmental heterogeneity, multivariate sexual selection and genetic constraints on cuticular hydrocarbons in Drosophila simulans

Sexual selection is responsible for the evolution of many elaborate traits, but sexual trait evolution could be influenced by opposing natural selection as well as genetic constraints. As such, the evolution of sexual traits could depend heavily on the environment if trait expression and attractiveness vary between environments. Here, male Drosophila simulans were reared across a range of diets and temperatures, and we examined differences between these environments in terms of (i) the expression of male cuticular hydrocarbons (CHCs) and (ii) which male CHC profiles were most attractive to females. Temperature had a strong effect on male CHC expression, whereas the effect of diet was weaker. Male CHCs were subject to complex patterns of directional, quadratic and correlational sexual selection, and we found differences between environments in the combination of male CHCs that were most attractive to females, with clearer differences between diets than between temperatures. We also show that genetic covariance between environments is likely to cause a constraint on independent CHC evolution between environments. Our results demonstrate that even across the narrow range of environmental variation studied here, predicting the outcome of sexual selection can be extremely complicated, suggesting that studies ignoring multiple traits or environments may provide an over-simplified view of the evolution of sexual traits.

No association between sperm competition and sperm length variation across dung flies (Scathophagidae)

Sperm length is extremely variable across species, but a general explanation for this variation is lacking. However, when the risk of sperm competition is high, sperm length is predicted to be less variable within species, and there is some evidence for this in birds and social insects. Here, we examined intraspecific variation in sperm length, both within and between males, and its potential associations with sperm competition risk and variation in female reproductive tract morphology across dung flies. We used two measures of variation in sperm size, and testis size was employed as our index of sperm competition risk. We found no evidence of associations between sperm length variation and sperm competition or female reproductive tract variation. These results suggest that variation in sperm competition risk may not always be associated with variation in sperm morphology, and the cause(s) of sperm length variation in dung flies remains unclear.

Reprogrammed foxp3(+) regulatory T cells provide essential help to support cross-presentation and CD8(+) T cell priming in naive mice

Foxp3(+) regulatory T (Treg) cells can undergo reprogramming into a phenotype expressing proinflammatory cytokines. However, the biologic significance of this conversion remains unclear. We show that large numbers of Treg cells undergo rapid reprogramming into activated T helper cells after vaccination with antigen plus Toll-like receptor 9 (TLR-9) ligand. Helper activity from converted Treg cells proved essential during initial priming of CD8(+) T cells to a new cross-presented antigen. Help from Treg cells was dependent on CD40L, and (unlike help from conventional non-Treg CD4(+) cells) did not require preactivation or prior exposure to antigen. In hosts with established tumors, Treg cell reprogramming was suppressed by tumor-induced indoleamine 2,3-dioxygenase (IDO) and vaccination failed because of lack of help. Treg cell reprogramming, vaccine efficacy, and antitumor CD8(+) T cell responses were restored by pharmacologic inhibition of IDO. Reprogrammed Treg cells can thus participate as previously unrecognized drivers of certain early CD8(+) T cell responses.

IDO activates regulatory T cells and blocks their conversion into Th17-like T cells

TLR ligands are effective vaccine adjuvants because they stimulate robust proinflammatory and immune effector responses and they abrogate suppression mediated by regulatory T cells (Tregs). Paradoxically, systemic administration of high doses of CpGs that bind to TLR9 ligands stimulated Tregs in mouse spleen to acquire potent suppressor activity dependent on interactions between programmed death-1 and its ligands. This response to CpG treatment manifested 8-12 h and was mediated by a rare population of plasmacytoid dendritic cells (CD19(+) pDC) induced to express the immunosuppressive enzyme IDO after TLR9 ligation. When IDO was blocked, CpG treatment did not activate Tregs, but instead stimulated pDCs to uniformly express the proinflammatory cytokine IL-6, which in turn reprogrammed Foxp3-lineage Tregs to express IL-17. Thus, CpG-induced IDO activity in pDCs acted as a pivotal molecular switch that induced Tregs to acquire a stable suppressor phenotype, while simultaneously blocking CpG-induced IL-6 expression required to reprogram Tregs to become Th17-like effector T cells. These findings support the hypothesis that IDO dominantly controls the functional status of Tregs in response to inflammatory stimuli in physiological settings.

Plasmacytoid dendritic cells from mouse tumor-draining lymph nodes directly activate mature Tregs via indoleamine 2,3-dioxygenase

A small population of plasmacytoid DCs (pDCs) in mouse tumor-draining LNs can express the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO). We show that these IDO+ pDCs directly activate resting CD4+CD25+Foxp3+ Tregs for potent suppressor activity. In vivo, Tregs isolated from tumor-draining LNs were constitutively activated and suppressed antigen-specific T cells immediately ex vivo. In vitro, IDO+ pDCs from tumor-draining LNs rapidly activated resting Tregs from non-tumor-bearing hosts without the need for mitogen or exogenous anti-CD3 crosslinking. Treg activation by IDO+ pDCs was MHC restricted, required an intact amino acid-responsive GCN2 pathway in the Tregs, and was prevented by CTLA4 blockade. Tregs activated by IDO markedly upregulated programmed cell death 1 ligand 1 (PD-L1) and PD-L2 expression on target DCs, and the ability of Tregs to suppress target T cell proliferation was abrogated by antibodies against the programmed cell death 1/PD-L (PD-1/PD-L) pathway. In contrast, Tregs activated by anti-CD3 crosslinking did not cause upregulation of PD-Ls, and suppression by these cells was unaffected by blocking the PD-1/PD-L pathway. Tregs isolated from tumor-draining LNs in vivo showed potent PD-1/PD-L-mediated suppression, which was selectively lost when tumors were grown in IDO-deficient hosts. We hypothesize that IDO+ pDCs create a profoundly suppressive microenvironment within tumor-draining LNs via constitutive activation of Tregs.

Inhibition of indoleamine 2,3-dioxygenase in dendritic cells by stereoisomers of 1-methyl-tryptophan correlates with antitumor responses

Indoleamine 2,3-dioxygenase (IDO) is an immunosuppressive enzyme that contributes to tolerance in a number of biological settings. In cancer, IDO activity may help promote acquired tolerance to tumor antigens. The IDO inhibitor 1-methyl-tryptophan is being developed for clinical trials. However, 1-methyl-tryptophan exists in two stereoisomers with potentially different biological properties, and it has been unclear which isomer might be preferable for initial development. In this study, we provide evidence that the D and L stereoisomers exhibit important cell type-specific variations in activity. The L isomer was the more potent inhibitor of IDO activity using the purified enzyme and in HeLa cell-based assays. However, the D isomer was significantly more effective in reversing the suppression of T cells created by IDO-expressing dendritic cells, using both human monocyte-derived dendritic cells and murine dendritic cells isolated directly from tumor-draining lymph nodes. In vivo, the d isomer was more efficacious as an anticancer agent in chemo-immunotherapy regimens using cyclophosphamide, paclitaxel, or gemcitabine, when tested in mouse models of transplantable melanoma and transplantable and autochthonous breast cancer. The D isomer of 1-methyl-tryptophan specifically targeted the IDO gene because the antitumor effect of D-1-methyl-tryptophan was completely lost in mice with a disruption of the IDO gene (IDO-knockout mice). Taken together, our findings support the suitability of D-1-methyl-tryptophan for human trials aiming to assess the utility of IDO inhibition to block host-mediated immunosuppression and enhance antitumor immunity in the setting of combined chemo-immunotherapy regimens.

Effect of Plant Growth Regulators on Growth, Yield and Quality of Chilli (Capsicum annuum L.) at Rampur, Chitwan

The present investigation was carried out in the plain areas of Chitwan to determine the promising plant growth regulators (PGR) promoting growth and yield of chilli cultivars Jwala and Suryamukhi during winter-summer season of 2003/2004. Suryamukhi ranked superior to Jwala for most of the yield attributing characters, whereas Jwala was better in vegetative characters than Suryamukhi. Among PGRs, 2,4-D at 2 ppm was better for fruit set, number of fruits per plant, fruit length, number of seeds per fruit, seed weight per fruits, 1000 seed weight and fruit yield where as NAA at 40 ppm gave the highest leaf area index (LAI). PGRs were ineffective in promoting flowering and fruiting during winter season. GA3 at 10 ppm exhibited maximum amount of ascorbic acid content. The treatments, 2 ppm 2,4-D, 5 ppm triacontanol, 40 ppm NAA and 10 ppm GA3 produced 28.75%, 25.70%, 13.61% and 2.30% higher fruit yield over control, respectively. The highest net profit and B:C ratio were recorded in case of 2 ppm 2,4-D. The use of GA3 as foliar spray was not economical. Key words: 2,4-D, NAA, triacontanol, GA3, leaf area index, net profit, B:C ratio J. Inst. Agric. Anim. Sci. 27:65-68 (2006)

GCN2 kinase in T cells mediates proliferative arrest and anergy induction in response to indoleamine 2,3-dioxygenase

Indoleamine 2,3 dioxygenase (IDO) catabolizes the amino acid tryptophan. IDO-expressing immunoregulatory dendritic cells (DCs) have been implicated in settings including tumors, autoimmunity, and transplant tolerance. However, the downstream molecular mechanisms by which IDO functions to regulate T cell responses remain unknown. We now show that IDO-expressing plasmacytoid DCs activate the GCN2 kinase pathway in responding T cells. GCN2 is a stress-response kinase that is activated by elevations in uncharged tRNA. T cells with a targeted disruption of GCN2 were not susceptible to IDO-mediated suppression of proliferation in vitro. In vivo, proliferation of GCN2-knockout T cells was not inhibited by IDO-expressing DCs from tumor-draining lymph nodes. IDO induced profound anergy in responding wild-type T cells, but GCN2-knockout cells were refractory to IDO-induced anergy. We hypothesize that GCN2 acts as a molecular sensor in T cells, allowing them to detect and respond to conditions created by IDO.

Expression of indoleamine 2,3-dioxygenase by plasmacytoid dendritic cells in tumor-draining lymph nodes

One mechanism contributing to immunologic unresponsiveness toward tumors may be presentation of tumor antigens by tolerogenic host APCs. We show that mouse tumor-draining LNs (TDLNs) contained a subset of plasmacytoid DCs (pDCs) that constitutively expressed immunosuppressive levels of the enzyme indoleamine 2,3-dioxygenase (IDO). Despite comprising only 0.5% of LN cells, these pDCs in vitro potently suppressed T cell responses to antigens presented by the pDCs themselves and also, in a dominant fashion, suppressed T cell responses to third-party antigens presented by nonsuppressive APCs. Adoptive transfer of DCs from TDLNs into naive hosts created profound local T cell anergy, specifically toward antigens expressed by the transferred DCs. Anergy was prevented by targeted disruption of the IDO gene in the DCs or by administration of the IDO inhibitor drug 1-methyl-D-tryptophan to recipient mice. Within the population of pDCs, the majority of the functional IDO-mediated suppressor activity segregated with a novel subset of pDCs coexpressing the B-lineage marker CD19. We hypothesize that IDO-mediated suppression by pDCs in TDLNs creates a local microenvironment that is potently suppressive of host antitumor T cell responses.

Expression of indoleamine 2,3-dioxygenase by plasmacytoid dendritic cells in tumor-draining lymph nodes

One mechanism contributing to immunologic unresponsiveness toward tumors may be presentation of tumor antigens by tolerogenic host APCs. We show that mouse tumor-draining LNs (TDLNs) contained a subset of plasmacytoid DCs (pDCs) that constitutively expressed immunosuppressive levels of the enzyme indoleamine 2,3-dioxygenase (IDO). Despite comprising only 0.5% of LN cells, these pDCs in vitro potently suppressed T cell responses to antigens presented by the pDCs themselves and also, in a dominant fashion, suppressed T cell responses to third-party antigens presented by nonsuppressive APCs. Adoptive transfer of DCs from TDLNs into naive hosts created profound local T cell anergy, specifically toward antigens expressed by the transferred DCs. Anergy was prevented by targeted disruption of the IDO gene in the DCs or by administration of the IDO inhibitor drug 1-methyl-D-tryptophan to recipient mice. Within the population of pDCs, the majority of the functional IDO-mediated suppressor activity segregated with a novel subset of pDCs coexpressing the B-lineage marker CD19. We hypothesize that IDO-mediated suppression by pDCs in TDLNs creates a local microenvironment that is potently suppressive of host antitumor T cell responses.

Ligation of B7-1/B7-2 by human CD4+ T cells triggers indoleamine 2,3-dioxygenase activity in dendritic cells

Human monocyte-derived dendritic cells (DCs) are capable of expressing the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO), which allows them to suppress Ag-driven proliferation of T cells in vitro. In DCs that express IDO, the activity of the enzyme is tightly regulated, with the protein being constitutively expressed, but functional activity requiring an additional set of triggering signals supplied during Ag presentation. We now show that triggering of functional IDO obligately requires ligation of B7-1/B7-2 molecules on the DCs by CTLA4/CD28 expressed on T cells. When this interaction was disrupted, IDO remained in the inactive state, and the DCs were unable to inhibit T cell proliferation. Inhibition could be fully restored by direct Ab-mediated cross-linking of B7-1/B7-2. Although both CD4(+) and CD8(+) T cells were susceptible to inhibition once IDO was induced, the ability to trigger functionally active IDO was strictly confined to the CD4(+) subset. Thus, the ability of CD4(+) T cells to induce IDO activity in DCs allowed the CD4(+) population to dominantly inhibit proliferation of the CD8(+) population via the bridge of a conditioned DC. We hypothesize that IDO activation via engagement of B7-1/B7-2 molecules on DCs, specifically, engagement by CTLA4 expressed on regulatory CD4(+) T cells, may function as a physiologic regulator of T cell responses in vivo.

Hyperresolving phase-only filters with an optically addressable liquid crystal spatial light modulator

Hyperresolving (sometimes called 'superresolving' or 'ultraresolving') phase-only filters can be generated using an optically addressable liquid crystal spatial light modulator. This approach avoids the problems of low efficiency, and coupling between amplitude and phase modulation, that arise when using conventional liquid crystal modulators. When addressed by a programmed light intensity distribution, it allows filters to be changed rapidly to modify the response of a system or permit the investigation of different filter designs. In this paper we present experimental hyperresolved images obtained using an optically addressable parallel-aligned nematic LCD with two zone Toraldo type phase-only filters. The images are compared with theoretical predictions.

Pattern of recruitment of immunoregulatory antigen-presenting cells in malignant melanoma

The mechanism by which the immune system of a tumor-bearing host acquires tolerance toward tumor antigens is still elusive. Antigen-presenting cells (APCs) are critical regulators of the decision between immune response and tolerance. APCs that express the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) have been found to inhibit T-cell responses both in vitro and in vivo. We hypothesized that malignant tumors exploit this mechanism by recruiting IDO-expressing APCs to the tumor-draining lymph nodes. To test this hypothesis, archival tissues and records of 26 cases of lymph node dissection for invasive cutaneous melanoma were obtained. IDO immunohistochemistry was performed on 14 cutaneous tumors and 328 regional lymph nodes. Abnormal accumulations of IDO-positive cells with a monocytoid or plasmacytoid morphology were identified in the perisinusoidal regions of draining lymph nodes in 45% of nodes studied. Recruitment of IDO-positive cells was seen in nodes with and without malignancy. We hypothesize that these IDO-positive APCs may contribute mechanistically to acquired tolerance to tumor antigens. Immunostaining of tumor-draining lymph nodes for abnormal accumulation of IDO-expressing cells might thus constitute an adverse prognostic factor and could contribute to the decision process and the appropriate care of patients with this deadly disease.

Potential regulatory function of human dendritic cells expressing indoleamine 2,3-dioxygenase

Antigen-presenting cells (APCs) can induce tolerance or immunity. We describe a subset of human APCs that express indoleamine 2,3-dioxygenase (IDO) and inhibit T cell proliferation in vitro. IDO-positive APCs constituted a discrete subset identified by coexpression of the cell-surface markers CD123 and CCR6. In the dendritic cell (DC) lineage, IDO-mediated suppressor activity was present in fully mature as well as immature CD123+ DCs. IDO+ DCs could also be readily detected in vivo, which suggests that these cells may represent a regulatory subset of APCs in humans.

Dyslipidaemia in African Americans, Hispanics and whites with type 2 diabetes mellitus and hypertension

AIM

To study the pattern of dyslipidaemia in African American, Hispanic, and White patients with type 2 diabetes mellitus and/or hypertension.

METHODS

The data were collected retrospectively on 6450 patients followed in the Harris County Hospital District Community Clinics. The information collected from review of the charts included each patient's age, sex, race, body mass index (b.m.i.), duration of type 2 diabetes mellitus and hypertension, medications, fasting plasma glucose, haemoglobin A1c, and fasting lipid profile. Mean lipid and haemoglobin A1c levels in the three ethnic groups were compared. The risk of abnormal cholesterol and triglyceride levels was assessed with logistic regression analysis.

RESULTS

The results show that in patients with type 2 diabetes mellitus after correcting for age, sex and b.m.i., African Americans have the lowest serum triglyceride concentrations and Whites have the highest values. This trend holds true even in patients with hypertension and in patients with both hypertension and type 2 diabetes mellitus. The risk of having abnormal triglycerides is 74% lower in African Americans, and 42% lower in Hispanics than Whites based on logistic regression model. Despite better glycaemic control, Whites have a greater increase in serum triglyceride concentrations than Hispanics and African Americans.

CONCLUSIONS

Although African Americans are known to be at higher risk for cardiovascular complications than Whites or Hispanics, they appear to have lower triglyceride concentrations than Whites or Hispanics in the presence of type 2 diabetes mellitus. This suggests that an increased prevalence of other adverse factors must contribute to their heightened cardiovascular risk.

High frequency of serious infections in patients with panhypopituitarism: a case-control study

We reviewed the records of 65 patients with panhypopituitarism (PHP) for the frequency and types of infections requiring hospitalization, and documented serious infections in 13 of 65 patients with PHP. The increased frequency of serious infectious diseases in patients with PHP is likely to contribute to increased age-specific mortality.

Induction and inhibition of CD40-CD40 ligand interactions: a new strategy underlying host-virus relationships

Interaction between CD40 and the CD40 ligand (CD40L) is required for mouse mammary tumor virus (MMTV) propagation. We found that Fas was expressed on B cells and CD40L on a small subset of viral superantigen-cognate T cells 12 h after MMTV(SW) infection. CD40L and Fas were down-regulated after 24 h. All CD4 T cells then became resistant to anti-CD3-induced CD40L induction in vitro for 2 wk. Initiation of CD40L expression and its rapid shut-off was associated with IL-12 production and was controlled by IFN-gamma and shedding of soluble CD40. These results suggest that a rapid, transient CD40-CD40L interaction involving a small number of cells is sufficient for MMTV propagation. Modulation of CD40L expression may be a major mechanism regulating the balance between viral propagation and host defenses, allowing mutual survival.

Induction and Inhibition of CD40-CD40 Ligand Interactions: A New Strategy Underlying Host-Virus Relationships

Interaction between CD40 and the CD40 ligand (CD40L) is required for mouse mammary tumor virus (MMTV) propagation. We found that Fas was expressed on B cells and CD40L on a small subset of viral superantigen-cognate T cells 12 h after MMTV(SW) infection. CD40L and Fas were down-regulated after 24 h. All CD4 T cells then became resistant to anti-CD3-induced CD40L induction in vitro for 2 wk. Initiation of CD40L expression and its rapid shut-off was associated with IL-12 production and was controlled by IFN-γ and shedding of soluble CD40. These results suggest that a rapid, transient CD40-CD40L interaction involving a small number of cells is sufficient for MMTV propagation. Modulation of CD40L expression may be a major mechanism regulating the balance between viral propagation and host defenses, allowing mutual survival.

Holmium-doped optical fiber for filter applications

We consider the properties of holmium-doped fibers in filter applications. We give spectral properties and model filter characteristics. Experiments on filtering of Raman spectra are presented. The fiber filters exhibit strong rejection in the stop band and sharp absorption cutoffs.

Isolation of the novel agent from human stool samples that is associated with sporadic non-A, non-B hepatitis

The agent(s) responsible for sporadic non-A, non-B hepatitis in humans was serially transmitted in rhesus monkeys by intravenous inoculation of the stool extract from a patient. A novel agent called HFV (hepatitis French [origin] virus) was present as 27- to 37-nm particles in the infectious stool extract. Hepatopathic lesions were noticed in infected monkeys during the acute phase of illness. The purified viral 27- to 37-nm particles consist of a double-stranded DNA of approximately 20 kb and are detected in infected monkey liver. Analysis of cell culture detects the approximately 20-kb-long viral DNA in stool samples from infected monkeys and sporadic enteric non-A, non-B hepatitis patients. Furthermore, the 27- to 37-nm viral particles were able to protect monkeys challenged with infectious stool extract. Our results indicate that 27- to 37-nm virus like particles are responsible for sporadic non-A, non-B hepatitis in rhesus monkeys.

Serial passage of west-European sporadic non-A non-B hepatitis in rhesus monkeys by inoculation with fecal extracts

An experimental model of sporadic non-A non-B hepatitis involving a Fab nonimmune binding activity in stools was established in the rhesus monkey. The first animal was inoculated intravenously with a stool extract from a French patient who had never left the country and in whom post-transfusion hepatitis was excluded. Four passages were performed, and the infection was transmitted by parenteral as well as the oral routes by inoculation of stools or liver extracts. Infection led in three monkeys to reversible hepatocyte injury manifested by a transitory increase in serum aminotransferases. The other three animals, in which persistently high levels of aminotransferases was observed, were sacrificed on day 60 after inoculation. The incubation period, as evidenced by elevation of aminotransferases was about 3 to 4 weeks. The infectious agent was transitorily present in the stools before aminotransferase elevation. The presence of the infectious agent in the stools was correlated with the nonimmune Fab binding activity.