Soluble TREM-like transcript-1 regulates leukocyte activation and controls microbial sepsis

The triggering receptor expressed on myeloid cells (TREM)-1 plays a crucial role during the onset of sepsis by amplifying the host immune response. The TREM-like transcript-1 (TLT-1) belongs to the TREM family, is selectively expressed on activated platelets, and is known to facilitate platelet aggregation through binding to fibrinogen. In this study, we show that a soluble form of TLT-1 is implicated in the regulation of inflammation during sepsis by dampening leukocyte activation and modulating platelet-neutrophil crosstalk. A 17-aa sequence of the TLT-1 extracellular domain (LR17) is responsible for this activity through competition with the TREM-1 ligand. Whereas early or late LR17 treatment of septic mice improves survival, treml-1(-/-) animals are highly susceptible to polymicrobial infection. The present findings identify platelet-derived soluble TLT-1 as a potent endogenous regulator of sepsis-associated inflammation and open new therapeutic perspectives. We anticipate soluble TLT-1 to be important in regulating leukocyte activation during other noninfectious inflammatory disorders.

Inhibition of thrombin-induced platelet aggregation using human single-chain Fv antibodies specific for TREM-like transcript-1

TREM-like transcript-1 (TLT-1) is a novel platelet membrane receptor, which has been recently characterized in mice. TLT-1 is expressed exclusively in platelets and megakaryocytes, and its expression is dramatically upregulated upon platelet activation, suggesting that it plays a unique role in hemostasis and/or thrombosis. In this study we identified and characterized highly specific human monoclonal antibodies that bind to TLT-1 by screening a naïve library of single chain Fv fragments (scFvs) displayed on filamentous phage (Thomlinson I library). These scFvs detected plate-bound TLT-1, captured soluble TLT-1, and readily reacted with cell-bound TLT-1 on transfectants and primary human platelets. Most importantly, anti-TLT-1 scFvs inhibited thrombin-mediated human platelet aggregation. This inhibition was specific for thrombin-induced aggregation and was reversible with higher doses of agonist. These data are the first to demonstrate a biological role for TLT-1 and its potential as a therapeutic target. The human scFvs isolated in this study may represent novel anti-platelet therapeutic agents.

Downregulation of TREM-like transcript-1 and collagen receptor α2 subunit, two novel RUNX1-targets, contributes to platelet dysfunction in familial platelet disorder with predisposition to acute myelogenous leukemia

Germline RUNX1 mutations lead to thrombocytopenia and platelet dysfunction in familial platelet disorder with predisposition to acute myelogenous leukemia (AML). Multiple aspects of platelet function are impaired in these patients, associated with altered expression of genes regulated by RUNX1. We aimed to identify RUNX1-targets involved in platelet function by combining transcriptome analysis of patient and shRUNX1-transduced megakaryocytes (MK). Down-regulated genes included TREM-like transcript (TLT)-1 (TREML1) and the integrin subunit alpha (α)-2 (ITGA2) of collagen receptor α2-beta (β)-1, which are involved in platelet aggregation and adhesion, respectively. RUNX1 binding to regions enriched for H3K27Ac marks was demonstrated for both genes using chromatin immunoprecipitation. Cloning of these regions upstream of the respective promoters in lentivirus allowing mCherry reporter expression showed that RUNX1 positively regulates TREML1 and ITGA2, and this regulation was abrogated after deletion of RUNX1 sites. TLT-1 content was reduced in patient MK and platelets. A blocking anti-TLT-1 antibody was able to block aggregation of normal but not patient platelets, whereas recombinant soluble TLT-1 potentiated fibrinogen binding to patient platelets, pointing to a role for TLT-1 deficiency in the platelet function defect. Low levels of α2 integrin subunit were demonstrated in patient platelets and MK, coupled with reduced platelet and MK adhesion to collagen, both under static and flow conditions. In conclusion, we show that gene expression profiling of RUNX1 knock-down or mutated MK provides a suitable approach to identify novel RUNX1 targets, among which downregulation of TREML1 and ITGA2 clearly contribute to the platelet phenotype of familial platelet disorder with predisposition to AML.

The effect of oral deferoxamine on iron absorption in humans

Acute iron overdose is a serious cause of morbidity and mortality, however, optimal gastric decontamination procedures in iron overdose are unclear. In order to determine the effectiveness of oral deferoxamine mesylate solution in humans to prevent the absorption of iron in acute exposures, the following prospective case control crossover study was designed. Seven informed adult human volunteers were given an oral dose of 5 mg/kg elemental iron alone in a control phase and again in an experimental phase followed by a single equimolar dose of oral buffered deferoxamine solution. Plasma iron concentrations were determined spectrophotometrically for eight hours following administration of iron alone and following doses of iron with deferoxamine. There was no significant difference in peak iron concentration, time to peak iron concentration or area-under-the-curve between the two groups. Based on our results, equimolar doses of oral deferoxamine do not appear to decrease the absorption of low doses of oral iron in humans.

Advantages of q-PCR as a method of screening for gene targeting in mammalian cells using conventional and whole BAC-based constructs

We evaluate here the use of real-time quantitative PCR (q-PCR) as a method for screening for homologous recombinants generated in mammalian cells from either conventional gene-targeting constructs or whole BAC-based constructs. Using gene-targeted events at different loci, we show that q-PCR is a highly sensitive and accurate method for screening for conventional gene targeting that can reduce the number of clones requiring follow-up screening by Southern blotting. We further compared q-PCR to fluorescent in situ hybridization (FISH) for the detection of gene-targeting events using full-length BAC-based constructs designed to introduce mutations either into one gene or simultaneously into two adjacent genes. We find that although BAC-based constructs appeared to have high rates of homologous recombination when evaluated by FISH, screening by FISH was prone to false positives that were detected by q-PCR. Our results demonstrate the utility of q-PCR as a screening tool for gene targeting and further highlight potential problems with the use of whole BAC-based constructs for homologous recombination.

Peptide histidine isoleucine-induced elevations in ACTH and corticosterone in the rat

Peptide histidine isoleucine (PHI) is one of many neuropeptides found in both the periphery and the central nervous system (CNS). In the present work, we compared the effects of intravenous (IV) and hypothalamic (PVN) administration of PHI on plasma ACTH and corticosterone (CORT) secretion 2 h after the onset of light in fasted, freely moving male rats. The PVN administration of PHI (0.15, 0.30, 1.50, and 3.0 nmol/rat) elicited significant, dose-dependent increases in plasma ACTH and CORT concentrations that were maximal at 15 min postadministration and fell gradually over 60-120 min. The highest dose of PHI increased ACTH and CORT to 821% and 340% of time-matched control levels, respectively. The IV injection of PHI (3.0 nmol/rat) also raised plasma ACTH and CORT levels in these animals. However, the peak response (at 15 min postinjection) to the same dose of PHI was much lower following IV administration (ACTH 188% of control; CORT 210% of control) than after PVN administration. These results suggest that endogenous PHI may be a physiological regulator of ACTH and CORT secretion in rats and that the PVN is a major site for its action.

Evaluation of four disease management programs: evidence from blue cross blue shield of Louisiana

Aims: Chronic diseases impose a substantial healthcare burden. This study sought to evaluate the clinical and economic impact of new disease management (DM) programs, targeting four major chronic disease groups: diabetes, coronary heart disease (CHD)/hypertension (HTN), asthma/chronic obstructive pulmonary disease (COPD), and congestive heart failure (CHF)/chronic kidney disease (CKD).Materials and methods: Between March 1, 2015, and February 28, 2018, members with Blue Cross Blue Shield of Louisiana insurance were contacted and enrolled in a DM program if they were aged 18 years through 64 years, eligible for a DM program, and had not been previously enrolled in a DM program. Active enrollees of a DM program ("IN" group) were compared to members who were not yet enrolled ("OUT" group). Average per member per month (PMPM) costs were aggregated annually to document any descriptive trends. Multivariable model estimates were used to compare PMPM costs for all IN subjects and all OUT subjects. Total medical savings were evaluated for the following time intervals: 1-12 months, 13-24 months, and 25-36 months.Results: For all four DM programs, average costs PMPM trended upward over time for the OUT cohort, while they remained relatively stable for the IN cohort. Some evidence also showed that DM programs improved clinical outcomes, such as hemoglobin A1c values. A difference in difference analysis showed PMPM savings for all four programs combined of $31.61, $50.45, and $53.72 after 1, 2, and 3 years, respectively. Multivariable modeling results showed total savings after 3 years of $14,460,174 for all DM programs combined.Limitations: Although multivariable models adjusted for several clinical, demographic, and economic characteristics; it is possible that some important confounders were missing due to lack of data.Conclusions: DM programs implemented to control diabetes, CHD/HTN, CHF/CKD, and asthma/COPD are cost-effective and show some evidence of improved clinical outcomes.

Platelet-derived soluble TREM-Like Transcrip-1 (TLT-1) induces human and mouse Dendritic Cell activation through a TLR-4-dependent mechanism. (136.32)

Triggering Receptor Expressed on Myeloid Cells-Like Transcrip-1 (TLT-1) is a member of the multifunctional TREM family of receptors that also include TREM-1, 2, 3, and TLT-2. TLT-1 is expressed on megakaryocytes and platelets at low levels, but upon activation with thrombin, its membrane expression is up-regulated and shed, yielding a soluble form (sTLT-1). Here we describe for the first time the ability of human sTLT-1 to activate human monocytes and antigen-presenting cells. Treatment of myeloid Dendritic Cells (DCs) with sTLT-1 resulted in an increase of co-stimulatory molecules, induction of pro-inflammatory cytokines production, and their ability to prime lymphocyte proliferation. sTLT-1 failed to activate murine Bone Marrow-derived Dendritic Cells from TLR4-deficient mice, and blocking antibodies against TLR4 reduced sTLT-1-induced cytokine production by human monocytes and DCs, indicating that TLR4 is involved in sTLT-1 signaling. Therefore, human sTLT-1 has the ability to endow APCs with the capacity to initiate adaptive immune responses, and may therefore be a potential target of anti-inflammatory therapies.

Abstract B29: Anti-breast cancer effects of the Vav/Rac inhibitor Ehop-016 in the tumor microenvironment

Metastatic breast cancer still lacks effective treatment, and remains the primary cause of mortality. Therefore, new effective strategies to inhibit breast cancer metastasis are needed. The Rho family GTPase Rac is an ideal target for anti-metastatic cancer therapy, because Rac is a key molecular switch that can promote cancer cell migration/invasion and survival. Previously, we reported the design and development of EHop-016, a small molecule compound, which inhibits Rac activation by the oncogene Vav in metastatic cancer cells with an IC50 of 1 microM. Consequently, EHop-016 inhibits the activity of the Rac downstream effector p21-activated kinase (PAK) and cell migration in metastatic breast cancer cells; and significantly reduces tumor growth, metastasis, and angiogenesis in a mouse model of metastatic breast cancer. The reduced tumor angiogenesis in response to EHop-016 treatment may be attributed to the inhibition of the Vav/Rac activity of endothelial cells, as shown by the ability of EHop-016 to inhibit the Rac activation and capillary tube formation of endothelial cells, in vitro. Recent studies have also shown a pivotal role for tumor associated stromal cells in signaling to the cancer cells to leave the primary tumor to initiate metastasis. Because Ehop-016 acts as a specific inhibitor of the Vav/Rac interaction, we hypothesize that EHop-016 inhibits the Vav/Rac signaling in not only cancer cells, but also in fibroblasts and leukocytes. To determine whether EHop-016 treatment affects the tumor microenvironment (TME), athymic nude mice bearing mammary fatpad tumors were treated with vehicle or 30 mg/kg BW EHop-016 by IP, 3X a week, for 52 days. Immunofluorescence microscopy of mammary tumor tissue sections demonstrated a statistically significant 40% decrease in Ki-67 expression, a 60% decrease in capillary tubes as quantified by CD-31 staining, and a 33% decrease in F4/80 positive macrophages in the tumors from mice following EHop-016 treatment, compared to those treated with vehicle. To investigate the effect of EHop-016 on the cytokine milieu, plasma recovered from the mice in this study were subjected to a cytokine array for common inflammatory mediators. EHop-016 treatment demonstrated a statistically significant decrease in mouse plasma levels of the major inflammatory mediator interleukin-6 (IL-6) that has been implicated with cancer progression in the TME, as well as a trend in reduced monocyte chemoattractant protein and tumor necrosis factor alpha. A PCR array analysis of the mammary tumors from this study also demonstrated a decrease in IL-6 levels in tumor tissue. Reduced macrophages and IL-6 signaling in the TME, in response to EHop-016 treatment, is expected to decrease the cytokine-mediated malignant signaling cross talk between cancer cells and stromal cells. Therefore, inhibition of Vav/Rac signaling in the TME may additionally enhance the anti-metastatic effects of EHop-016.

This study was supported by National Institute on Minority Health and Health Disparities of the National Institutes of Health (NIMHHD/NIH) U54MD008149 and the Puerto Rico Science and Technology Trust to SD; Title V PPOHA P031M10505 and Title V Cooperative P031S130068 from U.S. Department of Education, and RCMI 8G12MD007583 to UCC; and UPR RCM NIH/NIMHHD grants 5U54CA096297 andR25GM061838 to THB.

Citation Format: Linette Castillo-Pichardo, Cristina Del Valle, Jessica Morales, Valance Washington, Krizia Rohena-Rivera, Magaly Martinez, Luis Cubano, Suranganie Dharmawardhane. Anti-breast cancer effects of the Vav/Rac inhibitor Ehop-016 in the tumor microenvironment. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B29.

Ionic resorcinarenes as drug solubilization agents in water

Resorcinarenes are capable of host-guest complexation with small molecules, however, they are less studied as pharmaceutical drug delivery aids. This article reports on the aqueous-solubility enhancing effect of an octa-sulfonated resorcinarene and a C-hydroxybenzyl ammonium resorcinarene chloride on three hydrophobic drugs: isoniazid, caffeine, and griseofulvin. The findings are backed by dynamic light scattering, isothermal calorimetric titration, and nuclear magnetic resonance experiments in water. Aqueous mixtures of equal volumes of drug compounds and resorcinarene solutions produced a more soluble and clearer unit than solutions of pure drug compounds in water. Light scattering experiments revealed shifts in particle sizes of pure drug compounds to the range of resorcinarene hosts. 1H NMR measurements of resorcinarene-drug mixtures confirmed interactions with shift changes ranging from -0.20 to 0.81 ppm. Binding affinities quantified through ITC experiments ranged between 0.54 and 211 mM, signifying interactions between resorcinarenes and drug compounds necessary for the solubility of the drugs. Cytotoxicity studies suggest that resorcinarenes alone, or complexed with any of the drug compounds, do not exert cytotoxicity in mammalian cells HEK-293 up to 200 μM. We herein propose a set of hydrophilic resorcinarene macrocycles as potential drug solubilizers.