A Slc38a8 Mouse Model of FHONDA Syndrome Faithfully Recapitulates the Visual Deficits of Albinism Without Pigmentation Defects

Purpose

We aimed to generate and phenotype a mouse model of foveal hypoplasia, optic nerve decussation defects, and anterior segment dysgenesis (FHONDA), a rare disease associated with mutations in Slc38a8 that causes severe visual alterations similar to albinism without affecting pigmentation.

Methods

The FHONDA mouse model was generated with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology using an RNA guide targeting the Scl38a8 murine locus. The resulting mice were backcrossed to C57BL/6J. Melanin content was measured using spectrophotometry. Retinal cell architecture was analyzed through light and electron microscopy. Retinal projections to the brain were evaluated with anterograde labelling in embryos and adults. Visual function was assessed by electroretinography (ERG) and the optomotor test (OT).

Results

From numerous Slc38a8 mouse mutant alleles generated, we selected one that encodes a truncated protein (p.196Pro*, equivalent to p.199Pro* in the human protein) closely resembling a mutant allele described in patients (p.200Gln*). Slc38a8 mutant mice exhibit wild-type eye and coat pigmentation with comparable melanin content. Subcellular abnormalities were observed in retinal pigment epithelium cells of Slc38a8 mutant mice. Anterograde labeling experiments of retinal projections in embryos and adults showed a reduction of ipsilateral fibers. Functional visual analyses revealed a decreased ERG response in scotopic conditions and a reduction of visual acuity in mutant mice measured by OT.

Conclusions

Slc38a8 mutant mice recapitulate the phenotype of patients with FHONDA concerning their normal pigmentation and their abnormal visual system, in the latter being a hallmark of all types of albinism. These mice will be helpful in better understanding the pathophysiology of this genetic condition.

98 Peroxisome proliferator-activated receptor-gamma (PPARG) is dispensable for bovine blastocyst formation

Prostaglandins (PGs) are lipid signalling molecules that play critical roles in gestation by promoting corpus luteus maintenance or luteolysis, and have been suggested to play other roles in early pregnancy, including embryo–maternal crosstalk. The signalling roles of PGs and other lipids are often mediated by peroxisome proliferator-activated receptors (PPARs), transcription factors that regulate the expression of other genes through PPAR-responsive elements. PPARG is a PPAR expressed by bovine pre-implantation embryos whose inhibition by morpholino intrauterine infusion has been reported to impair embryo development. As this approach causes PPARG depletion in both conceptus and uterus, it is unknown whether PPARG-mediated signalling in the embryo is required for embryo development. The objective of this study was to determine whether PPARG is required for blastocyst formation. For that aim, we have evaluated embryo development in PPARG knockout (KO) bovine embryos generated by CRISPR-Cas9 technology. Invitro matured oocytes were allocated in two groups: one was injected with mRNA encoding for Cas9 and sgRNA against PPARG to generate KO embryos (C+G, n=191) and the other was injected with mRNA alone (C, n=148), serving as a microinjection control generating only wild-type embryos. Following fertilization, embryos were allowed to develop to Day 8 blastocysts invitro. No differences were found in cleavage and blastocyst rates between both groups (cleavage 78.5±3.4 vs. 78.4±4.2; Day 7 blastocyst 17.3±3.9 vs. 10.8±2.9; Day 8 blastocyst 20.4±6.2 vs. 16.9±4.7; C+G vs. C; mean±s.e.m.; ANOVA P>0.05). Blastocysts of the C+G group were genotyped by clonal sequencing to determine which embryos in the C+G group were KO (i.e. harboured only frame-disrupting, KO alleles). Twenty-eight out of the 32 blastocysts analysed were edited (87.5%), of which 6 (18.8%) were KO. These results show that PPARG is not required for blastocyst formation, because KO embryos develop to that stage, but do not rule out a possible role in further developmental stages.

Embryonic disc formation following post-hatching bovine embryo development in vitro

Failures during conceptus elongation are a major cause of pregnancy losses in ungulates, exerting a relevant economic impact on farming. The developmental events occurring during this period are poorly understood, mainly because this process cannot be recapitulated in vitro. Previous studies have established an in vitro post-hatching development (PHD) system that supports bovine embryo development beyond the blastocyst stage, based on agarose gel tunnels and serum- and glucose-enriched medium. Unfortunately, under this system embryonic disc formation is not achieved and embryos show notorious signs of apoptosis and necrosis. The objective of this study has been to develop an in vitro system able to support embryonic disc formation. We first compared post-hatching development inside agarose tunnels or free-floating over an agarose-coated dish in serum- and glucose-enriched medium (PHD medium). Culture inside agarose tunnels shaped embryo morphology by physical constriction, but it restricted embryo growth and did not provide any significant advantage in terms of development of hypoblast and epiblast lineages. In contrast to PHD medium, a chemically defined and enriched medium (N2B27) supported complete hypoblast migration and epiblast survival in vitro, even in the absence of agarose coating. Cells expressing the pluripotency marker SOX2 were observed in ~56% of the embryos and ~25% developed embryonic disc-like structures formed by SOX2+ cells. In summary, here we provide a culture system that supports trophectoderm proliferation, hypoblast migration and epiblast survival after the blastocyst stage.

Characterization of the immune response induced by pertussis OMVs-based vaccine

For the development of a third generation of pertussis vaccine that could improve the control of the disease, it was proposed that the immune responses induced by the classic whole cell vaccine (wP) or after infection should be used as a reference point. We have recently identified a vaccine candidate based on outer membrane vesicles (OMVs) derived from the disease etiologic agent that have been shown to be safe and protective in mice model of infection. Here we characterized OMVs-mediated immunity and the safety of our new candidate. We also deepen the knowledge of the induced humoral response contribution in pertussis protection. Regarding the safety of the OMVs based vaccine (TdapOMVsBp,) the in vitro whole blood human assay here performed, showed that the low toxicity of OMVs-based vaccine previously detected in mice could be extended to human samples. Stimulation of splenocytes from immunized mice evidenced the presence of IFN-γ and IL-17-producing cells, indicated that OMVs induces both Th1 and Th17 response. Interestingly TdapOMVsBp-raised antibodies such as those induced by wP and commercial acellular vaccines (aP) which contribute to induce protection against Bordetella pertussis infection. As occurs with wP-induced antibodies, the TdapOMVsBp-induced serum antibodies efficiently opsonized B. pertussis. All the data here obtained shows that OMVs based vaccine is able to induce Th1/Th17 and Th2 mixed profile with robust humoral response involved in protection, positioning this candidate among the different possibilities to constitute the third generation of anti-pertussis vaccines.

Delivering wasp venom for cancer therapy

Cytolytic peptides with potential therapeutic properties have appeared during the last three decades. However, the use of these natural weapons is relatively narrow due to their non-specific cytolytic activity as well as their rapid degradation and excretion when injected in blood. In order to rescue the use of these lytic peptides, we have designed pro-cytotoxic systems based on cytotoxic peptides conjugated to poly(l-glutamic acid) PGA polymer through specific cleavage sequences that are sensitive over-expressed tumor proteases, such as the metalloproteinase-2 (MMP-2) or cathepsin B. The potent cytotoxic peptide tested here, Mitoparan, is inactive when conjugated to the polymer and then become active again once released through the tumor proteases. Furthermore, this pro-cytotoxic system was decorated by a particular targeting peptide which binds to HER2 receptors over-expressed in some types of breast tumor cells, thereby increasing the selective release of cytolytic peptides inside tumor cell with exquisite spatiotemporal control. In this way, the system would improve the maximum tolerated dose and the pharmacokinetic parameters of cytotoxic peptides in vivo.

Outer membrane vesicles derived from Bordetella parapertussis as an acellular vaccine against Bordetella parapertussis and Bordetella pertussis infection

Bordetella parapertussis, a close related species of B. pertussis, can also cause the disease named pertussis or whooping cough. The number of cases caused by this related pathogen has risen sustained in the last years. The widely used cellular (wP) or acellular (aP) pertussis vaccines have little or no efficacy against B. parapertussis. In an effort to devise an effective acellular vaccine against B. parapertussis infection, outer membrane vesicles (OMVs) were obtained from B. parapertussis. Proteomic analysis of the resulting OMVs, designated OMVsBpp, evidenced the presence of several surface immunogens including pertactin. The characterized OMVsBpp were used in murine B. parapertussis intranasal challenge model to examine their protective capacity when administered by systemic route. Immunized BALB/c mice were challenged with sublethal doses of B. parapertussis. Significant differences between immunized animals and the negative control group were observed (p<0.001). OMVsBpp protected against B. parapertussis infection, whereas current commercial aP vaccine showed little protection against such pathogen. More interestingly, protection induced by OMVsBpp against B. pertussis was comparable to our previously designed vaccine consisting in OMVs derived from B. pertussis (OMVsBp). For these experiments we used as a positive control the current commercial aP vaccine in high dose. As expected aP offered protection against B. pertussis in mice. Altogether the results presented here showed that the OMVs from B. parapertussis are an attractive vaccine candidate to protect against whooping cough induced by B. parapertussis but also by B. pertussis.

Delivery of gold nanoparticles to the brain by conjugation with a peptide that recognizes the transferrin receptor

The treatment of Alzheimer's disease and many other brain-related disorders is limited because of the presence of the blood-brain barrier, which highly regulate the crossing of drugs. Metal nanoparticles have unique features that could contribute to the development of new therapies for these diseases. Nanoparticles have the capacity to carry several molecules of a drug; furthermore, their unique physico-chemical properties allow, for example, photothermal therapy to produce molecular surgery to destroy tumor cells and toxic structures. Recently, we demonstrated that gold nanoparticles conjugated to the peptide CLPFFD are useful to destroy the toxic aggregates of β-amyloid, similar to the ones found in the brains of patients with Alzheimer's disease. However, nanoparticles, like many other compounds, have null or very low capacity to cross the blood-brain barrier. In order to devise a strategy to improve drug delivery to the brain, here we introduced the peptide sequence THRPPMWSPVWP into the gold nanoparticle-CLPFFD conjugate. This peptide sequence interacts with the transferrin receptor present in the microvascular endothelial cells of the blood-brain barrier, thus causing an increase in the permeability of the conjugate in brain, as shown by experiments in vitro and in vivo. Our results are highly relevant for the therapeutic applications of gold nanoparticles for molecular surgery in the treatment of neurodegenerative diseases such as Alzheimer's disease.

Selenomethionine incorporation into amyloid sequences regulates fibrillogenesis and toxicity

Background

The capacity of a polypeptide chain to engage in an amyloid formation process and cause a conformational disease is contained in its sequence. Some of the sequences undergoing fibrillation contain critical methionine (Met) residues which in vivo can be synthetically substituted by selenomethionine (SeM) and alter their properties.

Methodology/Principal Findings

Using peptide synthesis, biophysical techniques and cell viability determinations we have studied the effect of the substitution of methionine (Met) by selenomethionine (SeM) on the fibrillogenesis and toxic properties of Aβ40 and HuPrP(106–140). We have found that the effects display site-specificity and vary from inhibition of fibrillation and decreased toxicity ([SeM³⁵]Aβ40, [SeM¹²⁹]HuPrP(106–140) and [SeM¹³⁴]HuPrP(106–140)), retarded assembly, modulation of polymer shape and retention of toxicity ([SeM¹¹²]HuPrP(106–140) to absence of effects ([SeM¹⁰⁹]HuPrP(106–140)).

Conclusions/Significance

This work provides direct evidence that the substitution of Met by SeM in proamyloid sequences has a major impact on their self-assembly and toxic properties, suggesting that the SeM pool can play a major role in dictating the allowance and efficiency of a polypeptide chain to undergo toxic polymerization.

Melanin precursors prevent premature age-related and noise-induced hearing loss in albino mice

Strial melanocytes are required for normal development and correct functioning of the cochlea. Hearing deficits have been reported in albino individuals from different species, although melanin appears to be not essential for normal auditory function. We have analyzed the auditory brainstem responses (ABR) of two transgenic mice: YRT2, carrying the entire mouse tyrosinase (Tyr) gene expression-domain and undistinguishable from wild-type pigmented animals; and TyrTH, non-pigmented but ectopically expressing tyrosine hydroxylase (Th) in melanocytes, which generate the precursor metabolite, L-DOPA, but not melanin. We show that young albino mice present a higher prevalence of profound sensorineural deafness and a poorer recovery of auditory thresholds after noise-exposure than transgenic mice. Hearing loss was associated with absence of cochlear melanin or its precursor metabolites and latencies of the central auditory pathway were unaltered. In summary, albino mice show impaired hearing responses during ageing and after noise damage when compared to YRT2 and TyrTH transgenic mice, which do not show the albino-associated ABR alterations. These results demonstrate that melanin precursors, such as L-DOPA, have a protective role in the mammalian cochlea in age-related and noise-induced hearing loss.

Diketopiperazines as a Tool for the Study of Transport across the Blood−Brain Barrier (BBB) and Their Potential Use as BBB-Shuttles

Here we prepared and evaluated two libraries of mono-N-methylated and di-N-methylated diketopiperazines (DKPs) by parallel artificial membrane permeability assay and immobilized artificial membrane chromatography in order to obtain information on the features that govern the passage of peptidic molecules across the blood-brain barrier (BBB) by passive diffusion. On the basis of the results from these two libraries, we prepared and evaluated several DKP-baicalin and DKP-dopamine constructs. The DKPs or cyclic dipeptide scaffolds can be considered a novel family of brain delivery systems (BBB-shuttles) to transport to the brain drugs and other cargos that cannot cross the BBB unaided.

Evolutionary combinatorial chemistry, a novel tool for SAR studies on peptide transport across the blood-brain barrier. Part 2. Design, synthesis and evaluation of a first generation of peptides

The use of high-throughput methods in drug discovery allows the generation and testing of a large number of compounds, but at the price of providing redundant information. Evolutionary combinatorial chemistry combines the selection and synthesis of biologically active compounds with artificial intelligence optimization methods, such as genetic algorithms (GA). Drug candidates for the treatment of central nervous system (CNS) disorders must overcome the blood-brain barrier (BBB). This paper reports a new genetic algorithm that searches for the optimal physicochemical properties for peptide transport across the blood-brain barrier. A first generation of peptides has been generated and synthesized. Due to the high content of N-methyl amino acids present in most of these peptides, their syntheses were especially challenging due to over-incorporations, deletions and DKP formations. Distinct fragmentation patterns during peptide cleavage have been identified. The first generation of peptides has been studied by evaluation techniques such as immobilized artificial membrane chromatography (IAMC), a cell-based assay, log Poctanol/water calculations, etc. Finally, a second generation has been proposed.

Arylboronic Acids and Arylpinacolboronate Esters in Suzuki Coupling Reactions Involving Indoles. Partner Role Swapping and Heterocycle Protection

Yields of Suzuki couplings involving indoles depended upon (i) whether arylboronic acids or arylpinacolboronate esters were used, (ii) whether the heterocycle was the aryl halide or the arylboron coupling partner, and (iii) whether the heterocycle was protected or not. Highest yields, which were unaffected by incorporating Boc or Tos protection at the heterocyclic nitrogen, were obtained when indole bromides were reacted with phenylboronic acids. When indolylboronic acids were reacted with phenyl bromides, yields were somewhat lower and depended on the nitrogen substituent, being highest in the absence of protection, lower in the presence of the Boc group, and lowest of all with the Tos group. Arylpinacolboronate esters were less reactive than arylboronic acids. They required considerably longer reaction times and furnished generally lower yields of biaryl. Furthermore, irrespective of whether the heterocycle was the aryl bromide or the arylpinacolboronate ester, these yields were highest when it was protected with the Tos group. Yields were lower with the Boc group, and unprotected heterocycles gave only traces of biaryl. Careful selection of arylboron reagent, of coupling partner roles, and of protecting groups are essential to ensuring optimum results in these Suzuki couplings. These results may also be relevant to couplings involving other substrates.

[Focal nodular hyperplasia of the liver with malignant endoscopy appearance]

We report the case of a male patient, 49 years of age, who was admitted to our hospital to clarify the diagnosis of a solid liver tumor of the left lobe of the liver which had been made by image methods (U.S., scan and scintigraphy). Laparoscopy showed an isolated tumor emerging from the left lobe of the liver featuring hypervascularity and umbilication at the top. A visual diagnosis of malignancy was made which was not confirmed neither by biopsy nor the cytological examination. Liver resection was undertaken, and a diagnosis of nodular hyperplasia was made by the pathologist. We have never encountered before this endoscopic appearance of focal nodular hyperplasia either in our own experience or in the search of the literature.