Iminosugar C-Glycosides Work as Pharmacological Chaperones of NAGLU, a Glycosidase Involved in MPS IIIB Rare Disease*

Mucopolysaccharidosis type IIIB is a devastating neurological disease caused by a lack of the lysosomal enzyme, α-N-acetylglucosaminidase (NAGLU), leading to a toxic accumulation of heparan sulfate. Herein we explored a pharmacological chaperone approach to enhance the residual activity of NAGLU in patient fibroblasts. Capitalizing on the three-dimensional structures of two modest homoiminosugar-based NAGLU inhibitors in complex with bacterial homolog of NAGLU, CpGH89, we have synthesized a library of 17 iminosugar C-glycosides mimicking N-acetyl-D-glucosamine and bearing various pseudo-anomeric substituents of both α- and β-configuration. Elaboration of the aglycon moiety results in low micromolar selective inhibitors of human recombinant NAGLU, but surprisingly it is the non-functionalized and wrongly configured β-homoiminosugar that was proved to act as the most promising pharmacological chaperone, promoting a 2.4 fold activity enhancement of mutant NAGLU at its optimal concentration.

Synthesis and chelation study of a fluoroionophore and a glycopeptide based on an aza crown iminosugar structure

Capitalizing on a recently reported iminosugar-based aza-crown (ISAC) accessed by a double Staudinger azaWittig coupling reaction, we have expanded the structural diversity of this new family of sweet cyclam analogs. Replacement of the two secondary amines linking the iminosugar units by two amide bonds obtained a cyclodimerization by with BOP and DIPEA led to a macrocycle that did not demonstrate efficient Zn²⁺ chelation unlike the parent ISAC. Introduction of two pyrene moieties on the secondary amines of the parent ISAC yielded a new fluoroionophore that selectively binds Hg²⁺ in methanol.

Ginnalin B induces differentiation markers and modulates the proliferation/differentiation balance via the upregulation of NOTCH1 in human epidermal keratinocytes

The red maple and sugar maple (Acer rubrum and A. saccharum, respectively) contain acertannins (ginnalins and maplexins), galloylated derivatives of 1,5-anhydro-d-glucitol (1,5-AG, 1). These compounds have a variety of potential medicinal properties and we have shown that some of them promote the expression of ceramide synthase 3. We now report on the beneficial effects of ginnalin B, (6-O-galloyl-1,5-AG, 5), leading to acceleration of skin metabolism and reduction of the turnover time. Ginnalin B dose-dependently increased the relative amount of keratin 10, keratin 1, and filaggrin gene, with maximal increase of 1.7-, 2.9, and 5.2-fold at 100 μM, respectively. The validation study showed that it had superior capacity to induce multiple stages of keratinocyte differentiation and significantly elevated the immunostaining site of keratin 10 and filaggrin in a 3-dimensional cultured human skin model, by 1.2 and 2.8-fold, respectively. Furthermore, ginnalin B caused the arrest of proliferation at the G₀/G₁ phase but it did not induce apoptotic cell death in normal human keratinocytes. Molecular studies revealed that ginnalin B up-regulated the levels of NOTCH1 and a concomitant increase p21 expression. Ginnalin B, therefore, represents a new class of promising functional and medical cosmetic compound and it could contribute to the maintenance of homeostasis of the epidermis.

Subcutaneous Fusarium foot abscess in a renal transplant patient

Fusarium species are ubiquitous plant and grain phytopathogens that rarely cause opportunistic infections in immunocompromised patients. While disseminated Fusarium infections are almost always fatal, localized infections may be responsive to a combination of systemic antibiotic therapy and surgical debridement. We present a diabetic renal transplant patient who developed a foot abscess due to Fusarium solani. Infection persisted despite aggressive surgical debridement and a 3-month course of intravenous liposomal amphotericin B.

Tumor-specific peptides in cutaneous T-cell lymphoma: association with class I major histocompatibility complex and possible derivation from the clonotypic T-cell receptor

We wished to identify and characterize tumor-associated class I peptides which could potentially serve as immunogens for an immunoprotective CD8 response in cutaneous T-cell lymphoma (CTCL). Candidate idiotypic peptides were identified from the third complementarity determining region (CDR3) of the clonotypic T-cell receptor (TCR) expressed on malignant T cells and native class I peptides were identified from CTCL cells. Idiotypic peptides were designed by sequencing of patients' CDR3 and identifying 9 amino acid peptides that could be accommodated in the peptide-binding motif of the class I alleles. Three candidate idiotypic peptides were synthesized and tested by measuring release of tumor necrosis factor-alpha (TNF-alpha) from autologous CD8 cells. Native peptides were acid-eluted from class I molecules on CTCL lymphocytes, fractionated, tested in the TNF-alpha assay and sequenced. Two unique idiotypic peptides were specifically recognized by autologous CD8 cells from CTCL patients. In addition, a native peptide eluted from class I molecules of CTCL tumor cells was identified, in the protein data base, as a novel molecule with partial sequence homology to the conserved portion of the patient's TCR. This homology was used to construct an extended native peptide sequence that was immunogenic for CD8 cells from both CTCL patients. Our results demonstrate that peptides derived from the TCR can be used as tumor-specific immunogens that are recognized by CD8 cells. Moreover, novel class I peptides isolated from the tumor cell also serve as immunogens. These peptides might form the basis of an anti-tumor vaccine for immunotherapy of CTCL.

Induction of functional empty class I major histocompatibility complex glycoproteins by photoactivated 8-methoxypsoralen

CD8+ cytotoxic T lymphocytes (CTLs) bind to and selectively lyse tumor cells via T-cell receptor recognition of distinctive peptide antigens presented in the context of surface major histocompatibility complex class I (MHC class I) glycoproteins. Several human and experimental animal tumors express distinctive MHC class I-associated peptides, which can be selectively targeted by specific CD8+ CTLs. Malignant cells expressing low quantities of these peptides are poor inducers of CTL responses. Therefore, we have developed a method of externally loading increased amounts of antigenic peptides onto MHC class I molecules. In order to induce "empty" fillable MHC class I molecules capable of binding antigenic peptides, we exposed transformed murine T cells (RMA) to low dose (3 joules/cm2) ultraviolet A energy and 8-methoxypsoralen (100 ng per ml). Presence of "empty" class I molecules was ascertained by "meltdown" or loss of the thermodynamically unstable cold-induced "empty" molecules as identified by cytofluorography at 37 degrees C. Retained function of "empty" molecules was determined by their stabilization through addition of peptides of the correct size and sequence motif, prior to exposure to physiologic temperature.

TAP1-dependent peptide translocation in vitro is ATP dependent and peptide selective

T cells detect infection of cells by recognizing peptide fragments of foreign proteins bound to class I molecules of the major histocompatibility complex (MHC) on the surface of the infected cell. MHC class I molecules bind peptide in the endoplasmic reticulum, and analysis of mutant cells has demonstrated that an adequate supply of peptides requires the presence of two genes in the MHC class II locus that encode proteins called transporters associated with antigen processing (TAP) 1 and 2. TAP1 and TAP2 are members of the ATP-binding cassette family of membrane translocators. In this study, we demonstrate in a cell-free system that TAP1 is part of an ATP-dependent, sequence-specific, peptide translocator.

Treatment of multiple apocrine hidrocystomas with the carbon dioxide (CO2) laser

The apocrine hidrocystoma tends to occur as a solitary facial cystic lesion. We report an unusual patient in whom there were multiple apocrine hidrocystomas scattered over the periorbital region and ears. Although solitary apocrine hidrocystomas are easily treated with excision, we had good results employing carbon dioxide laser vaporization in the treatment of numerous hidrocystomas.