High Dose Pharmaceutical Grade Biotin (MD1003) Accelerates Differentiation of Murine and Grafted Human Oligodendrocyte Progenitor Cells In Vivo

Accumulating evidences suggest a strong correlation between metabolic changes and neurodegeneration in CNS demyelinating diseases such as multiple sclerosis (MS). Biotin, an essential cofactor for five carboxylases, is expressed by oligodendrocytes and involved in fatty acid synthesis and energy production. The metabolic effect of biotin or high-dose-biotin (MD1003) has been reported on rodent oligodendrocytes in vitro, and in neurodegenerative or demyelinating animal models. However, clinical studies, showed mild or no beneficial effect of MD1003 in amyotrophic lateral sclerosis (ALS) or MS. Here, we took advantage of a mouse model of myelin deficiency to study the effects of MD1003 on the behavior of murine and grafted human oligodendrocytes in vivo. We show that MD1003 increases the number and the differentiation potential of endogenous murine oligodendroglia over time. Moreover, the levels of MD1003 are increased in the plasma and brain of pups born to treated mothers, indicating that MD1003 can pass through the mother's milk. The histological analysis of the grafted animals shows that MD1003 increased proliferation and accelerates differentiation of human oligodendroglia, but without enhancing their myelination potential. These findings provide important insights into the role of MD1003 on murine and human oligodendrocyte maturation/myelination that may explain the mitigated outcome of ALS/MS clinical trials.

Humanized zebrafish as a tractable tool for in vivo evaluation of pro-myelinating drugs

Therapies that promote neuroprotection and axonal survival by enhancing myelin regeneration are an unmet need to prevent disability progression in multiple sclerosis. Numerous potentially beneficial compounds have originated from phenotypic screenings but failed in clinical trials. It is apparent that current cell- and animal-based disease models are poor predictors of positive treatment options, arguing for novel experimental approaches. Here we explore the experimental power of humanized zebrafish to foster the identification of pro-remyelination compounds via specific inhibition of GPR17. Using biochemical and imaging techniques, we visualize the expression of zebrafish (zf)-gpr17 during the distinct stages of oligodendrocyte development, thereby demonstrating species-conserved expression between zebrafish and mammals. We also demonstrate species-conserved function of zf-Gpr17 using genetic loss-of-function and rescue techniques. Finally, using GPR17-humanized zebrafish, we provide proof of principle for in vivo analysis of compounds acting via targeted inhibition of human GPR17. We anticipate that GPR17-humanized zebrafish will markedly improve the search for effective pro-myelinating pharmacotherapies.

Future Perspective of Diabetic Animal Models

Objective

The need of today’s research is to develop successful and reliable diabetic animal models for understanding the disease susceptibility and pathogenesis. Enormous success of animal models had already been acclaimed for identifying key genetic and environmental factors like Idd loci and effects of microorganisms including the gut microbiota. Furthermore, animal models had also helped in identifying many therapeutic targets and strategies for immune-intervention. In spite of a quite success, we have acknowledged that many of the discovered immunotherapies are working on animals and did not have a significant impact on human. Number of animal models were developed in the past to accelerate drug discovery pipeline. However, due to poor initial screening and assessment on inequivalent animal models, the percentage of drug candidates who succeeded during clinical trials was very low. Therefore, it is essential to bridge this gap between pre-clinical research and clinical trial by validating the existing animal models for consistency.

Results and Conclusion

In this review, we have discussed and evaluated the significance of animal models on behalf of published data on PUBMED. Amongst the most popular diabetic animal models, we have selected six animal models (e.g. BioBreeding rat, “LEW IDDM rat”, “Nonobese Diabetic (NOD) mouse”, “STZ RAT”, “LEPR Mouse” and “Zucker Diabetic Fatty (ZDF) rat” and ranked them as per their published literature on PUBMED. Moreover, the vision and brief imagination for developing an advanced and robust diabetic model of 21^st century was discussed with the theme of one mice-one human concept including organs-on-chips.

Humanized UGT2 and CYP3A transchromosomic rats for improved prediction of human drug metabolism

Genomically humanized animals overcoming species differences are invaluable for biomedical research. Although rats would be preferred over mice for several applications, generation of a humanized model is restricted to mice due to the difficulty of complex genetic manipulations in rats. In this study, we successfully generated humanized rats with megabase-sized gene clusters via combination of chromosome transfer using mouse artificial chromosome vector and genome editing technologies. In the humanized UGT2 and CYP3A transchromosomic rats described in this paper, the expression of the human genes, as well as the pharmacokinetics and metabolism of relevant probe substrates, accurately mimic the situation in humans. Thus, the advanced technologies can be used to generate fully humanized rats useful for biomedical research.

Although “genomically” humanized animals are invaluable tools for generating human disease models as well as for biomedical research, their development has been mainly restricted to mice via established transgenic-based and embryonic stem cell-based technologies. Since rats are widely used for studying human disease and for drug efficacy and toxicity testing, humanized rat models would be preferred over mice for several applications. However, the development of sophisticated humanized rat models has been hampered by the difficulty of complex genetic manipulations in rats. Additionally, several genes and gene clusters, which are megabase range in size, were difficult to introduce into rats with conventional technologies. As a proof of concept, we herein report the generation of genomically humanized rats expressing key human drug-metabolizing enzymes in the absence of their orthologous rat counterparts via the combination of chromosome transfer using mouse artificial chromosome (MAC) and genome editing technologies. About 1.5 Mb and 700 kb of the entire UDP glucuronosyltransferase family 2 and cytochrome P450 family 3 subfamily A genomic regions, respectively, were successfully introduced via the MACs into rats. The transchromosomic rats were combined with rats carrying deletions of the endogenous orthologous genes, achieved by genome editing. In the “transchromosomic humanized” rat strains, the gene expression, pharmacokinetics, and metabolism observed in humans were well reproduced. Thus, the combination of chromosome transfer and genome editing technologies can be used to generate fully humanized rats for improved prediction of the pharmacokinetics and drug–drug interactions in humans, and for basic research, drug discovery, and development.

Lycopene reduces ovarian tumor growth and intraperitoneal metastatic load

Mutagens like oxidants cause lesions in the DNA of ovarian and fallopian tube epithelial cells, resulting in neoplastic transformation. Reduced exposure of surface epithelia to oxidative stress may prevent the onset or reduce the growth of ovarian cancer. Lycopene is well-known for its excellent antioxidant properties. In this study, the potential of lycopene in the prevention and treatment of ovarian cancer was investigated using an intraperitoneal animal model. Lycopene prevention significantly reduced the metastatic load of ovarian cancer-bearing mice, whereas treatment of already established ovarian tumors with lycopene significantly diminished the tumor burden. Lycopene treatment synergistically enhanced anti-tumorigenic effects of paclitaxel and carboplatin. Immunostaining of tumor and metastatic tissues for Ki67 revealed that lycopene reduced the number of proliferating cancer cells. Lycopene decreased the expression of the ovarian cancer biomarker, CA125. The anti-metastatic and anti-proliferative effects were accompanied by down-regulated expression of ITGA5, ITGB1, MMP9, FAK, ILK and EMT markers, decreased protein expression of integrin α5 and reduced activation of MAPK. These findings indicate that lycopene interferes with mechanisms involved in the development and progression of ovarian cancer and that its preventive and therapeutic use, combined with chemotherapeutics, reduces the tumor and metastatic burden of ovarian cancer in vivo.

GARP inhibits allergic airway inflammation in a humanized mouse model

BACKGROUND

Regulatory T cells (Treg) represent a promising target for novel treatment strategies in patients with inflammatory/allergic diseases. A soluble derivate of the Treg surface molecule glycoprotein A repetitions predominant (sGARP) has strong anti-inflammatory and regulatory effects on human cells in vitro as well as in vivo through de novo induction of peripheral Treg. The aim of this study was to investigate the immunomodulatory function of sGARP and its possible role as a new therapeutic option in allergic diseases using a humanized mouse model.

METHODS

To analyze the therapeutic effects of sGARP, adult NOD/Scidγc(-/-) (NSG) mice received peripheral blood mononuclear cells (PBMC) derived from allergic patients with sensitization against birch allergen. Subsequently, allergic inflammation was induced in the presence of Treg alone or in combination with sGARP.

RESULTS

In comparison with mice that received Treg alone, additional treatment with sGARP reduced airway hyperresponsiveness (AHR), influx of neutrophils and macrophages into the bronchoalveolar lavage (BAL), and human CD45(+) cells in the lungs. Furthermore, the numbers of mucus-producing goblet cells and inflammatory cell infiltrates were reduced. To elucidate whether the mechanism of action of sGARP involves the TGF-β receptor pathway, mice additionally received anti-TGF-β receptor II (TGF-βRII) antibodies. Blocking the signaling of TGF-β through TGF-βRII abrogated the anti-inflammatory effects of sGARP, confirming its essential role in inhibiting the allergic inflammation.

CONCLUSION

Induction of peripheral tolerance via sGARP is a promising potential approach to treat allergic airway diseases.

Expression of Human DNAJ (Heat Shock Protein-40) B3 in Humanized UDP-glucuronosyltransferase 1 Mice

The human DNAJB3 gene encodes a DNAJ (Heat shock protein 40; Hsp40) homolog, subfamily B, member 3 chaperone protein (DNAJB3), which can be down-regulated in disease conditions, as observed in decreased expression of DNAJB3 mRNA in peripheral blood mononuclear cells (PBMC) of obese patients. Recently, humanized UDP-glucuronosyltransferase (UGT) 1 mice (hUGT1 mice) were developed, in which the introduced human UGT1 gene contained a gene encoding human DNAJB3. In the present study, we analyzed the expression of human DNAJB3 mRNA in hUGT1 mice. Among the examined tissues, the testis had the highest expression of human DNAJB3 mRNA, while the lowest expression was observed in the liver. We found that the pattern of tissue-specific expression of mouse Dnajb3 in hUGT1 mice was very similar to that of human DNAJB3. We further demonstrated that the expression of human DNAJB3 in the liver was significantly reduced in high-fat-diet-fed hUGT1 mice compared to the expression level in the control mice, indicating that the expression of human DNAJB3 in hUGT1 mice could be similarly regulated in disease conditions such as obesity. Humanized UGT1 mice might therefore be useful to investigate the physiological role of human DNAJB3 in vivo.

Subepidermal blistering induced by human autoantibodies to BP180 requires innate immune players in a humanized bullous pemphigoid mouse model

Bullous pemphigoid (BP) is a cutaneous autoimmune inflammatory disease associated with subepidermal blistering and autoantibodies against BP180, a transmembrane collagen and major component of the hemidesmosome. Numerous inflammatory cells infiltrate the upper dermis in BP. IgG autoantibodies in BP fix complement and target multiple BP180 epitopes that are highly clustered within a non-collagen linker domain, termed NC16A. Anti-BP180 antibodies induce BP in mice. In this study, we generated a humanized mouse strain, in which the murine BP180NC14A is replaced with the homologous human BP180NC16A epitope cluster region. We show that the humanized NC16A (NC16A+/+) mice injected with anti-BP180NC16A autoantibodies develop BP-like subepidermal blisters. The F(ab')(2) fragments of pathogenic IgG fail to activate the complement cascade and are no longer pathogenic. The NC16A+/+ mice pretreated with mast cell activation blocker or depleted of complement or neutrophils become resistant to BP. These findings suggest that the humoral response in BP critically depends on innate immune system players.

Subepidermal blistering induced by human autoantibodies to BP180 requires innate immune players in a humanized bullous pemphigoid mouse model

Bullous pemphigoid (BP) is a cutaneous autoimmune inflammatory disease associated with subepidermal blistering and autoantibodies against BP180, a transmembrane collagen and major component of the hemidesmosome. Numerous inflammatory cells infiltrate the upper dermis in BP. IgG autoantibodies in BP fix complement and target multiple BP180 epitopes that are highly clustered within a non-collagen linker domain, termed NC16A. Anti-BP180 antibodies induce BP in mice. In this study, we generated a humanized mouse strain, in which the murine BP180NC14A is replaced with the homologous human BP180NC16A epitope cluster region. We show that the humanized NC16A (NC16A+/+) mice injected with anti-BP180NC16A autoantibodies develop BP-like subepidermal blisters. The F(ab')(2) fragments of pathogenic IgG fail to activate the complement cascade and are no longer pathogenic. The NC16A+/+ mice pretreated with mast cell activation blocker or depleted of complement or neutrophils become resistant to BP. These findings suggest that the humoral response in BP critically depends on innate immune system players.

Experimental models for the autoimmune and inflammatory blistering disease, Bullous pemphigoid

Bullous pemphigoid (BP) is a subepidermal skin blistering disease characterized immunohistologically by dermal-epidermal junction (DEJ) separation, an inflammatory cell infiltrate in the upper dermis, and autoantibodies targeted toward the hemidesmosomal proteins BP230 and BP180. Development of an IgG passive transfer mouse model of BP that reproduces these key features of human BP has demonstrated that subepidermal blistering is initiated by anti-BP180 antibodies and mediated by complement activation, mast cell degranulation, neutrophil infiltration, and proteinase secretion. This model is not compatible with study of human pathogenic antibodies, as the human and murine antigenic epitopes are not cross-reactive. The development of two novel humanized mouse models for the first time has enabled study of disease mechanisms caused by BP autoantibodies, and presents an ideal in vivo system to test novel therapeutic strategies for disease management.