Normal Immune System Development in Mice Lacking the Deltex-1 RING Finger Domain

The Notch signaling pathway controls several cell fate decisions during lymphocyte development, from T-cell lineage commitment to the peripheral differentiation of B and T lymphocytes. Deltex-1 is a RING finger ubiquitin ligase which is conserved from Drosophila to humans and has been proposed to be a regulator of Notch signaling. Its pattern of lymphoid expression as well as gain-of-function experiments suggest that Deltex-1 regulates both B-cell lineage and splenic marginal-zone B-cell commitment. Deltex-1 was also found to be highly expressed in germinal-center B cells. To investigate the physiological function of Deltex-1, we generated a mouse strain lacking the Deltex-1 RING finger domain, which is essential for its ubiquitin ligase activity. Deltex-1(Δ/Δ) mice were viable and fertile. A detailed histological analysis did not reveal any defects in major organs. T- and B-cell development was normal, as were humoral responses against T-dependent and T-independent antigens. These data indicate that the Deltex-1 ubiquitin ligase activity is dispensable for mouse development and immune function. Possible compensatory mechanisms, in particular those from a fourth Deltex gene identified during the course of this study, are also discussed

Comparative analysis of the oral mucosae from rodents and non-rodents: Application to the nonclinical evaluation of sublingual immunotherapy products

<div><p>Background</p><p>A comparative characterization of the oral mucosa in various animals is needed to identify the best animal model(s) for nonclinical evaluation of sublingual immunotherapy products. With this aim, we studied the histological characteristics and immune cell infiltrates of oral mucosae from common animal species.</p><p>Methods</p><p>Three oral regions (<i>i</i>.<i>e</i>. ventral surface of the tongue, mouth floor and cheek) obtained from eight animal species, including rodents (<i>i</i>.<i>e</i>. mice, rats, hamsters, guinea pigs) and non-rodents (<i>i</i>.<i>e</i>. rabbits, dogs, minipigs and monkeys) were characterized by histology and immunohistology in comparison with a human tongue.</p><p>Results</p><p>Rodents exhibit a thin keratinized epithelium with low epithelial extensions, whereas non-rodents, most particularly minipigs and monkeys, display a non-keratinized epithelium with larger rete ridges, similarly to humans. Glycogen-rich cells in the superficial epithelial layers are observed in samples from both minipigs, monkeys and humans. Comparable immune subpopulations detected in the 3 oral regions from rodent and non-rodent species include MHC-II⁺ antigen presenting cells, mostly CD163⁺ macrophages, located in the <i>lamina propria</i> (<i>LP)</i> and muscle tissue in the vicinity of resident CD3⁺CD4⁺ T cells. Limited numbers of mast cells are also detected in the <i>LP</i> and muscle tissue from all species.</p><p>Conclusion</p><p>The oral mucosae of minipigs and monkeys are closest to that of humans, and the immune networks are quite similar between all rodents and non-rodents. Taking into account the ethical and logistical difficulties of performing research in the latter species, rodents and especially mice, should preferentially be used for pharmacodynamics/efficacy studies. Our data also support the use of minipigs to perform biodistribution and safety studies of sublingual immunotherapy products.</p></div

Detection of glycogen in the oral mucosae of mice, minipigs, monkeys and humans.

<p>Representative photomicrographs of mucosal (<i>i</i>.<i>e</i>. ventral surface of the tongue, mouth floor or cheek as indicated in the figure) tissue sections (magnification x400) embedded in paraffin and stained with PAS and PAS diastase are shown.</p

Mapping of immune cells in the ventral surface of tongues from rats, dogs, minipigs and monkeys.

<p>Mucosal tissues from animal species were processed for immunohistology analysis, as described in Methods. Slides were stained with the following specific antibodies: anti-MHC-II, anti-CD163, anti-CD172a, anti-CD3, and anti-CD4 to detect and quantify positive cells in tissue sections or with toluidine blue to quantify mast cells (magnification x200). Representative photomicrographs of mucosal tissue sections are shown.</p

Collagen fibers density in the mucosa of the ventral surface of tongues from rodents, non-rodent species and humans.

<p>Representative photomicrographs of mucosal (<i>i</i>.<i>e</i>. ventral surface of the tongue) tissue sections (magnification x200) embedded in paraffin and stained with Masson trichrome are shown.</p

Histology of the ventral surface of the tongue from rodents, non-rodent species and humans.

<p>Representative photomicrographs of mucosal (<i>i</i>.<i>e</i>. ventral surface of the tongue) tissue sections (magnification x400 for animal species and x200/x400 for human) embedded in paraffin and stained with Hematoxylin-Eosin (HE) are shown.</p