Effective uptake of folate-functionalized ethionamide-loaded hybrid system: targeting alveolar macrophages

Aim: To assess the targeting ability of hybrid nanosystems functionalized with folate. It also aimed to reduce stomach intolerance by substituting the oral route for parenteral delivery. Method: The nanosystems, prepared by nanoprecipitation technique, utilized a one-step method to prepare nanoparticles followed by surface functionalization through adsorption. The prepared nanosystems underwent physical characterization, in vitro and in vivo evaluations. Result: The nanosystems were effective in targeting the alveolar macrophages. Ethionamide was released from the formulation over 5 days. Fourier-transform infrared results proved the structural characteristics, and the positive charge further improved the targeting efficacy on the functionalized system. Conclusion: The hybrid formulation improved the release characteristics. Reduction in dosing frequency due to prolonged release improves compliance with the dosage regimen.

Runx1 Role in Epithelial and Cancer Cell Proliferation Implicates Lipid Metabolism and Scd1 and Soat1 Activity

The role of lipid metabolism in epithelial stem cell (SC) function and carcinogenesis is poorly understood. The transcription factor Runx1 is known to regulate proliferation in mouse epithelial hair follicle (HF) SCs in vivo and in several mouse and human epithelial cancers. We found a novel subset of in vivo Runx1 HFSC target genes related to lipid metabolism and demonstrated changes in distinct classes of lipids driven by Runx1. Inhibition of lipid-enzymes Scd1 and Soat1 activity synergistically reduces proliferation of mouse skin epithelial cells and of human skin and oral squamous cell carcinoma cultured lines. Varying Runx1 levels induces changes in skin monounsaturated fatty acids (e.g., oleate, a product of Scd1) as shown by our lipidome analysis. Furthermore, varying Runx1 levels, the inhibition of Scd1, or the addition of Scd1-product oleate, individually affects the plasma membrane organization (or fluidity) in mouse keratinocytes. These factors also affect the strength of signal transduction through the membranes for Wnt, a pathway that promotes epithelial (cancer) cell proliferation and HFSC activation. Our working model is that HFSC factor Runx1 modulates the fatty acid production, which affects membrane organization, facilitating signal transduction for rapid proliferation of normal and cancer epithelial cells. Stem Cells 2018;36:1603-1616.

In vitro directed evolution of alpha-hemolysin by liposome display

We have developed a method to enable in vitro directed evolution that can be applied to membrane proteins. This method, termed liposome display, uses liposomes as compartments in which membrane proteins are synthesized and as scaffolds for membrane protein integration. Thus, the synthesized membrane proteins are displayed on the surface of the liposome and exhibit their functions. A randomly mutated DNA library of the membrane protein was generated, encapsulated in the liposomes at the single-molecule level, and used to generate a liposome library. Liposomes displaying the desired membrane protein function were selected, thus accumulating the DNA molecule encoding the desired membrane protein. We have applied this method to alpha-hemolysin, a membrane protein derived from Staphylococcus aureus. Alpha-hemolysin forms a nanopore in the membrane, which allows the penetration of small molecules. We aimed to improve this nanopore activity by using the liposome display method. Consequently, alpha-hemolysin evolved and attained a higher specific affinity for the liposome membrane. In this review, we describe the essential characteristics of liposome display and the properties of the evolved alpha-hemolysin obtained by this method.

Heritability of fat accumulation in white adipocytes

Since individual cells from freshly isolated white adipose tissue (WAT) exhibit variable levels of fat accumulation, we attempted to determine which factor(s) cause this variation. We used primary WAT cells from adult mice and the mouse 3T3-L1 cell-line of preadipocytes for these studies. Cells were labeled with BODIPY (boron-dipyrromethene) lipid probe, a marker for fat accumulation in live cells, and sorted on a fluorescence-activated cell sorter into two populations exhibiting low or high BODIPY fluorescence intensity. After more than 12 doublings as dedifferentiated cells in growth medium, the sorted populations were exposed to adipogenic medium for 7 days and analyzed for BODIPY accumulation and mRNA expression of adipogenic markers. WAT-derived cells initially sorted to have low or high BODIPY fluorescence intensity maintained a similar low or high lipid phenotype after redifferentiation. Cell surface TSH receptor expression, which is known to increase when preadipocytes are differentiated, correlated with BODIPY staining in all states. mRNA levels of Pparγ, Srebp1c, aP2, and Pref1, key regulators of adipogenesis, and leptin, Glut4, Fasn, and Tshr, markers of adipocyte differentiation, correlated with the levels of fat accumulation. Overexpression of Pparγ in 3T3-L1 cells, as expected, caused cells from low- and high-BODIPY populations to accumulate more fat. More importantly, prior to differentiation, the endogenous Pparγ promoter exhibited higher levels of acetylated histone H3, an activatory modification, in high-BODIPY- compared with low-BODIPY-derived populations. We conclude that fat accumulation is a heritable trait in WAT and that epigenetic modification on the Pparγ promoter contributes to this heritability.

Tissue distribution and safety evaluation of a claudin-targeting molecule, the C-terminal fragment of Clostridium perfringens enterotoxin

We previously found that claudin (CL) is a potent target for cancer therapy using a CL-3 and -4-targeting molecule, namely the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE). Although CL-3 and -4 are expressed in various normal tissues, the safety of this CL-targeting strategy has never been investigated. Here, we evaluated the tissue distribution of C-CPE in mice. Ten minutes after intravenous injection into mice, C-CPE was distributed to the liver and kidney (24.0% and 9.5% of the injected dose, respectively). The hepatic level gradually fell to 3.2% of the injected dose by 3 h post-injection, whereas the renal C-CPE level gradually rose to 46.5% of the injected dose by 6 h post-injection and then decreased. A C-CPE mutant protein lacking the ability to bind CL accumulated in the liver to a much lesser extent (2.0% of the dose at 10 min post-injection) than did C-CPE, but its renal profile was similar to that of C-CPE. To investigate the acute toxicity of CL-targeted toxin, we intravenously administered C-CPE-fused protein synthesis inhibitory factor to mice. The CL-targeted toxin dose-dependently increased the levels of serum biomarkers of liver injury, but not of kidney injury. Histological examination confirmed that injection of CL-targeted toxin injured the liver but not the kidney. These results indicate that potential adverse hepatic effects should be considered in C-CPE-based cancer therapy.

Antitumour activity on extrinsic apoptotic targets of the triterpenoid maslinic acid in p53-deficient Caco-2 adenocarcinoma cells

We report that a novel triterpenoid, (2a,3b)-2,3-dihydroxyolean-12-en-28-oic acid (maslinic acid), isolated from olive pomace from Olea europaea, triggers primarily the extrinsic and later the intrinsic apoptotic pathways in Caco-2 human colon-cancer cells. Apoptosis induced by maslinic acid was confirmed by FACS analysis using annexine-V FICT staining. This induction of apoptosis was correlated with the early activation of caspase-8 and caspase-3, the activation of caspase-8 was also correlated with higher levels of Bid cleavage and decreased Bcl-2, but with no change in Bax expression. Maslinic acid also induced a sustained activation of c-Jun N-terminal kinase (JNK). Incubation with maslinic acid also resulted in the later activation of caspase-9, which, together with the lack of any Bax activation, suggests that the mitochondrial pathway is not required for apoptosis induced by maslinic acid in this cell line. In this study we found that the mechanism of apoptotic activation in p53-deficient Caco-2 cells differs significantly from that found in HT-29 cells. Natural agents able to activate both the extrinsic and intrinsic apoptotic pathways by avoiding the mitochondrial resistance mechanisms may be useful for treatment against colon cancer regardless of its aetiology.

An engineered Fc variant of an IgG eliminates all immune effector functions via structural perturbations

The Fc variant of IgG2, designated as IgG2σ, was engineered with V234A/G237A /P238S/H268A/V309L/A330S/P331S substitutions to eliminate affinity for Fcγ receptors and C1q complement protein and consequently, immune effector functions. IgG2σ was compared to other previously well-characterized Fc 'muted' variants, including aglycosylated IgG1, IgG2m4 (H268Q/V309L/A330S/P331S, changes to IgG4), and IgG4 ProAlaAla (S228P/L234A/L235A) in its capacity to bind FcγRs and activate various immune-stimulatory responses. In contrast to the previously characterized muted Fc variants, which retain selective FcγR binding and effector functions, IgG2σ shows no detectable binding to the Fcγ receptors in affinity and avidity measurements, nor any detectable antibody-dependent cytotoxicity, phagocytosis, complement activity, or Fc-mediated cytokine release. Moreover, IgG2σ shows minimal immunogenic potential by T-cell epitope analysis. The circulating half-life of IgG2σ in monkeys is extended relative to IgG1 and IgG2, in spite of similar in vitro binding to recombinant FcRn. The three-dimensional structure of the Fc, needed for assessing the basis for the absence of effector function, was compared with that of IgG2 revealing a number of conformational differences near the hinge region of the CH2 domain that result from the amino acid substitutions. Modeling reveals that at least one of the key interactions with FcγRs is disrupted by a conformational change that reorients P329 to a position that prevents it from interacting with conserved W90 and W113 residues of the FcγRs. Inspection of the structure also indicated significant changes to the conformations of D270 and P329 in the CH2 domain that could negatively impact C1q binding. Thus, structural perturbations of the Fc provide a rationale for the loss of function. In toto, these properties of IgG2σ suggest that it is a superior alternative to previously described IgG variants of minimal effector function, for future therapeutic applications of non-immunostimulatory mAb and Fc-fusion platforms.

A change in the number of CCSP(pos)/SPC(pos) cells in mouse lung during development, growth, and repair

BACKGROUND

Putative resident stem/progenitor cells have been identified in the bronchoalveolar duct junction (BADJ) of the murine lung. However, the contribution of stem cells expressing both Clara cell secretory protein (CCSP) and pro-surfactant protein C (SP-C) to the repair and maintenance of normal homeostasis is still unclear. In this study, we identified and then quantified CD45(neg)/CCSP(pos)/SP-C(pos) cell numbers in normal and lung-injured mice.

METHODS

Normal lung tissues of fetal, newborn, and adult mice were used to evaluate lung progenitor cells during development and growth. Mice treated with naphthalene were used for the bronchiolar epithelium injury model, and mice treated with bleomycin were used for the alveolar epithelium injury model. These lung tissues were stained with CD45, CCSP, and SP-C antibodies by immunofluorescence. The number of lung progenitor cells was counted as CD45(neg)/CCSP(pos)/SP-C(pos) cells by flow cytometry.

RESULTS

CCSP(pos)/SP-C(pos) epithelial cells in the BADJ were identified from E18 to 7 months after birth. The percentage of CD45(neg)/CCSP(pos)/SP-C(pos) cells was relatively stable to 7 months (between 0.3±0.04% and 1.28±0.11%). When lungs were treated with naphthalene, the proliferation of CCSP(pos)/SP-C(pos) cells was observed as patches of double-positive cells and preceded the recovery of bronchioles. In contrast, when lungs were treated with bleomycin, the proliferation of CCSP(pos)/SP-C(pos) cells was observed, but the type II alveolar epithelial cells never recovered to baseline.

CONCLUSIONS

CCSP(pos)/SP-C(pos) lung cells were stable until 7 months after birth. These cells in the BADJ primarily regenerate bronchiolar epithelial cells and not alveolar epithelial cells.

Alginate-coated chitosan nanogel capacity to modulate the effect of TLR ligands on blood dendritic cells

Biodegradable nanoparticles have been employed for vaccine delivery, frequently admixed with adjuvants. Surprisingly, there is little information on their modulation of immune responses, speculated to be negligible. We analyzed the immunomodulatory capacity of alginate-coated chitosan nanogels (Ng), on porcine and human blood dendritic cells (DCs), when applied with defined adjuvants targeting different DC subpopulations. DC maturation, cytokine production and cell migration were assessed. Ng differentially influenced the immunomodulatory characteristics of individual Toll-like receptor (TLR) ligands: Pam3Cys-SK4-induced IL-1β was enhanced; CpG-oligodeoxynucleotides (CpG-ODN)-induced IFN-α, IL-6 and TNFα were impaired; CpG-ODN-induced CD86 and CCR7, and cell migration, were diminished-plasmacytoid DCs (pDCs) were particularly sensitive. Therein, the Ng influence on DC endocytosis of the TLR ligands was apparently a major contributory element. This demonstrates the importance of predefining the interplay between delivery vehicles and admixed immunostimulatory moieties, for ensuring appropriate immune activation and efficacious combinations.

FROM THE CLINICAL EDITOR

Biodegradable nanoparticles have been utilized in vaccine delivery; however, there is little information available on their immunomodulatory properties, which are thought to be negligible. This study clearly demonstrates that nanogels do influence the developing immune response, which needs to be taken into consideration when utilizing these otherwise very efficacious vaccine delivery approaches.

High frequency of skin-homing melanocyte-specific cytotoxic T lymphocytes in autoimmune vitiligo

Vitiligo is an autoimmune condition characterized by loss of epidermal melanocytes. Using tetrameric complexes of human histocompatibility leukocyte antigen (HLA) class I to identify antigen-specific T cells ex vivo, we observed high frequencies of circulating MelanA-specific, A*0201-restricted cytotoxic T lymphocytes (A2-MelanA tetramer+ CTLs) in seven of nine HLA-A*0201-positive individuals with vitiligo. Isolated A2-MelanA tetramer+ CTLs were able to lyse A*0201-matched melanoma cells in vitro and their frequency ex vivo correlated with extent of disease. In contrast, no A2-MelanA tetramer+ CTL could be identified ex vivo in all four A*0201-negative vitiligo patients or five of six A*0201-positive asymptomatic controls. Finally, we observed that the A2-MelanA tetramer+ CTLs isolated from vitiligo patients expressed high levels of the skin homing receptor, cutaneous lymphocyte-associated antigen, which was absent from the CTLs seen in the single A*0201-positive normal control. These data are consistent with a role of skin-homing autoreactive melanocyte-specific CTLs in causing the destruction of melanocytes seen in autoimmune vitiligo. Lack of homing receptors on the surface of autoreactive CTLs could be a mechanism to control peripheral tolerance in vivo.

Clonal anergy: persistence in tolerant mice of antigen-binding B lymphocytes incapable of responding to antigen or mitogen

The purpose of these experiments was to determine the degree of reduction in the number of antigen-binding B lymphocytes in the spleens of mice that had been rendered tolerant in the perinatal period. Newborn or pregnant mice were injected with fluorescein (Flu) coupled onto human gamma globulin, and the spleen cells of the neonatally injected mice, or of the offspring of the pregnant mice, were analyzed 1-6 weeks later. Tolerogen doses were chosen so as to achieve either a two-thirds reduction (low dose) in the number of anti-Flu B cells capable of yielding anti-hapten plaque-forming cell clones after in vitro stimulation, or as representing a supra-optimal tolerogenic stimulus (high dose). Antigen-binding B cells were studied by a two-cycle procedure, namely an initial cycle of binding to Flu-gelatin thin layers, followed by analysis of the binding cells in the fluorescence-activated cell sorter (FACS) after suitable staining with Flu-protein conjugates. With the high dose of tolerogen, a modest diminution in Flu-binding cell numbers down to 56-71% of control values could be induced. When these residual Flu-specific B cells were analyzed in the FACS to quantitate their spectrum of Flu-binding avidities, profiles identical to those of controls were obtained. The reduction proved transient in nature, binding cell numbers having returned to 80% of normal by 2 weeks and to normal by 6 weeks. Nevertheless, the Flu-specific B cells were incapable of responding to antigen or mitogen by antibody formation. With the low dose of tolerogen, despite the desired degree of functional silencing of Flu-specific B cells, the numbers and avidity spectra of antigen-binding cells were entirely normal in both the neonatally injected and in utero-injected groups. The results indicate that tolerance induced amongst immature B lymphocytes is not due to a physical elimination of the relevant B cell clones or to a modulation or blockade of their surface Ig receptors. Rather, it is due to the recognition and storage of negative signals amongst cells that continue to display a normal complement of receptors. We therefore propose that the term "clonal anergy" is a more accurate description than either "clonal deletion" or "clonal abortion."

Time-dependent resistance or susceptibility of tumor cells to cytotoxic antibody after exposure to a chemotherapeutic agent

We report that a chemotherapeutic agent (melphalan) can affect the sensitivity of tumor cells to cytotoxic antibody. Depending on the time interval between drug treatment and subsequent exposure to antibody and complement, the tumor cells can be either more resistant or more susceptible to antibody when compared to control cells. The number of tumor cells surviving the combined treatment was determined by a colony inhibition assay. The two antisera used in this study were directed against either virus-specific or myeloma protein-specific antigens on the surface of S107 murine myeloma cells; identical results were obtained with both sera. Twenty-four hours after exposure to the drug, the number of tumor cells surviving the antibody treatment increased. During this period of increased resistance, the tumor cells were temporarily arrested in the G(2) phase of the cell cycle. After this period of maximal resistance, the effect of cytotoxic antibody on the cells changed such that 4 days after melphalan treatment the cells were significantly more susceptible to the antibody than were the sham-treated control cells. The period of increased susceptibility correlated with an increased density of S107 myeloma protein and viral antigens on the surface of the tumor cells. Eight days after the drug treatment, the susceptibility of the tumor cells and the density of surface antigens both returned to normal levels. This study shows that the correct time interval between exposure to a drug and subsequent treatment with antibody is critical for maximal killing of the tumor cells. The basis for the differential sensitivity of the tumor cells to anti-body may be related to the drug-induced changes in the cell cycle and in antigen expression on the cell surface.