Immunomodulation stimulates the innervation of engineered tooth organ

The sensory innervation of the dental mesenchyme is essential for tooth function and protection. Sensory innervation of the dental pulp is mediated by axons originating from the trigeminal ganglia and is strictly regulated in time. Teeth can develop from cultured re-associations between dissociated dental epithelial and mesenchymal cells from Embryonic Day 14 mouse molars, after implantation under the skin of adult ICR mice. In these conditions however, the innervation of the dental mesenchyme did not occur spontaneously. In order to go further with this question, complementary experimental approaches were designed. Cultured cell re-associations were implanted together with trigeminal ganglia for one or two weeks. Although axonal growth was regularly observed extending from the trigeminal ganglia to all around the forming teeth, the presence of axons in the dental mesenchyme was detected in less than 2.5% of samples after two weeks, demonstrating a specific impairment of their entering the dental mesenchyme. In clinical context, immunosuppressive therapy using cyclosporin A was found to accelerate the innervation of transplanted tissues. Indeed, when cultured cell re-associations and trigeminal ganglia were co-implanted in cyclosporin A-treated ICR mice, nerve fibers were detected in the dental pulp, even reaching odontoblasts after one week. However, cyclosporin A shows multiple effects, including direct ones on nerve growth. To test whether there may be a direct functional relationship between immunomodulation and innervation, cell re-associations and trigeminal ganglia were co-implanted in immunocompromised Nude mice. In these conditions as well, the innervation of the dental mesenchyme was observed already after one week of implantation, but axons reached the odontoblast layer after two weeks only. This study demonstrated that immunodepression per se does stimulate the innervation of the dental mesenchyme

Physiopathologie des maladies inflammatoires chroniques de l’intestin (MICI)

Les maladies inflammatoires chroniques de l’intestin (MICI) sont des pathologies multifactorielles complexes d’étiologie inconnue. Différentes mutations génétiques, l’exposition à des facteurs environnementaux ou une perte d’homéostasie du microbiote intestinal sont impliqués en proportions variables dans la perte de la fonction de barrière de la muqueuse, son invasion par les microorganismes intestinaux et finalement, le déclenchement d’une réponse inflammatoire excessive et chronique provoquant les lésions caractéristiques de ces pathologies. Différents composants du système immunitaire muqueux comme les cellules épithéliales intestinales, les cellules du système immunitaire inné et adaptatif et les médiateurs de l’inflammation sont impliqués dans la pathogenèse des MICI. D’autres mécanismes cellulaires comme des carences nutritionnelles, l’immuno-récepteur TREM-1 ainsi que l’autophagie amplifient l’inflammation intestinale et accentuent la sévérité de ces pathologies. Cette revue présente les différents mécanismes impliqués dans la physiopathologie des MICI en comparant les muqueuses intestinales saines et pathologiques.Inflammatory bowel disease (IBD) is a complex multifactorial pathology of unknown etiology. Different genetic mutations, exposition of environmental factors or the loss of intestinal microbiota homeostasis are contribute to the loss of intestinal mucosal barrier function, its invasion by intestinal microorganims and finally the activation of excessive and chronic inflammatory response, which induce the typical lesions found in these pathologies. Various components of the mucosal immune system such as intestinal epithelial cells, cells of the innate and adaptive immune system and the mediators of inflammation are involved in the pathogenesis of IBD. Other cellular mechanisms as nutritional deficiencies, TREM-1 immunoreceptor and autophagy amplify the intestinal inflammation and increase the severity of these pathologies. In this review, the different mechanisms involved in the pathophysiology of IBD will be presented by comparing healthy and pathological intestinal mucosa

Calorie Restriction as a New Treatment of Inflammatory Diseases

International audienceImmoderate calorie intake coupled with a sedentary lifestyle are major determinants of health issues and inflammatory diseases in modern society.The balance between energy consumption and energy expenditure is critical for longevity. Excessive energy intake and adiposity cause systemicinflammation, whereas calorie restriction (CR) without malnutrition, exerts a potent anti-inflammatory effect. The objective of this review was toprovide an overview of different strategies used to reduce calorie intake, discuss physiological mechanisms by which CR might lead to improvedhealth outcomes, and summarize the present knowledge about inflammatory diseases. We discuss emerging data of observational studies andrandomized clinical trials on CR that have been shown to reduce inflammation and improve human health. Adv Nutr 2021;00:1–13

Well-organized spheroids as a new platform to examine cell interaction and behaviour during organ development

We present an experimental method allowing the production of three-dimensional organ-like structures, namely microtissues (MTs), in vitro without the need for exogenous extracellular matrix (ECM) or growth factors. Submandibular salivary glands (embryonic day ED14), kidneys (ED13) and lungs (ED13) were harvested from mouse embryos and dissociated into single cells by enzyme treatment. Single cells were seeded into special hanging drop culture plates (InSphero) and cultured for up to 14 days to obtain MTs. This strategy permitted full control of the quantity of seeded cells. The development of the MTs into organs was followed histologically and immunohistochemically. Well-organized epithelial structures surrounded by a basal lamina were formed, as confirmed by transmission electron microscopy. Expression of E-cadherin, vimentin, fibronectin and alpha-SMA was compared in organs and corresponding MTs by real-time quantitative polymerase chain reaction. Branching morphogenesis was induced in MTs (as shown by histology and immunostaining for fibronectin and perlecan) and was conserved even after 14 days of culture. MTs continued their development and their epithelial structures were comparable with those of the physiological organ at postnatal day 2 (PN2). Expression of aquaporins was investigated to obtain better support for the functional differentiation of epithelial cells. Histogenesis proceeded and led to the start of organogenesis. This experimental model might improve our knowledge of epithelial-mesenchymal histogenesis and can be employed to study development or cellular organization during the embryonic formation of organs

Innervation of bioengineered teeth implanted in Nude mice.

<p>Bioengineered teeth germs were co-implanted with trigeminal ganglia in adult Nude mice <b>(A–J)</b> for 1 <b>(A–C)</b> or 2 weeks <b>(D–J)</b>. Nerve fibers and blood vessels in dental pulp and peridental tissues of bioengineered teeth were analysed immunohistochemically by using specific antibodies for peripherin and CD31. Blood vessels were present in peridental tissues and could enter in the dental pulp and reach odontoblasts already after 1 week of implantation <b>(A–C)</b>. The staining for peripherin showed that nerve fibers entered in the dental pulp <b>(A, D)</b> and extend in the pulp <b>(B, E)</b> after 1 <b>(A–C)</b> and 2 <b>(D–J)</b> weeks. After 1 week of implantation, nerve fibers did not reach the odontoblasts <b>(C)</b>. This was achieved only after 2 weeks of implantation <b>(F, G, I, J)</b>. Double staining for peripherin <b>(G–I)</b>, CD31 <b>(G)</b>, CD34 <b>(H)</b> and CD146 <b>(I)</b> showed associations between nerve fibers and blood vessels in the dental pulp <b>(H)</b> and subodontoblastic layer <b>(G, I)</b>. After 2 weeks of implantation, nerve fibers, visualized by anti-peripherin antibody, had reached the odontoblast (positive for nestin) layer <b>(J)</b>. Am, ameloblasts; D, dentin; DP, dental pulp; E, enamel; Od, odontoblasts; PDM, peridental mesenchyme; TG, trigeminal ganglia.</p

Sugars and Gastrointestinal Health

International audienc

Innervation of bioengineered teeth implanted in cyclosporin A-treated ICR mice by transmission electron microscopy.

<p>Transmission electron microscopy (TEM) of trigeminal ganglia <b>(A)</b> showed the presence of myelinated and unmyelinated axons surrounded by Schwann cells <b>(A)</b>. TEM of dental pulp of epithelial and mesenchymal cell-cell re-associations co-implanted for 2 weeks with trigeminal ganglia in CsA-treated ICR mice showed the presence of unmyelinated axons <b>(B)</b>. These axons were surrounded by a Schwann cell and located near fibroblasts, which secreted collagen <b>(B)</b>. In <b>C</b>, one unmyelinated axon was surrounded by a Schwann cell with a developed rough endoplasmic reticulum. Neurofilaments <b>(D, E)</b>, numerous secretory vesicles <b>(arrowheads in F and insert)</b> and mitochondria <b>(F)</b> were present in the axons. A typical structure of a pre-synapse with numerous mitochondria and synaptic vesicles <b>(arrowheads)</b> was observed <b>(F)</b>. Thickening of the membrane suggested presence of synaptic contacts <b>(arrows in E and F)</b>. Ax, myelinated axon; DP, dental pulp; F, fibroblasts; m, mitochondria; N, nucleus; NF, neurofilaments; My, myelin; RER, rough endoplasmic reticulum; SC, Schwann cells; *, unmyelinated axon.</p

Tooth organ engineering

B

Transmission electronic microscopy of bioengineered teeth implanted for 2 weeks in cyclosporin A-treated ICR mice.

<p>Odontoblasts, dentinogenesis <b>(A–D, G)</b> and ameloblasts-enamel <b>(E, F, H)</b> in bioengineered teeth implanted for 2 weeks in CsA-treated ICR mice were analysed by transmission electron microscopy. Elongated odontoblasts showed a polarized position of the nucleus <b>(A)</b>. A desmosome was observed between two odontoblasts <b>(B: arrows and insert)</b>. In the cytoplasm of odontoblasts, the rough endoplasmic reticulum, mitochondria and secretory vesicles <b>(arrowheads)</b> were present in the supra-nuclear area <b>(C)</b>. The insert in <b>C</b> showed a zonula adherens between two odontoblasts. Odontoblast processes were surrounded by collagen fibers from predentin <b>(D)</b>. Ameloblasts were elongated and their nuclei were distant from the secretory pole <b>(E)</b>, which contained numerous vesicles <b>(F, arrowheads and insert)</b>. The junction between predentin and mineralized dentin was clearly visible <b>(G)</b>. The insert in <b>G</b> showed the typical periodic striation of collagen fibers. The dental-enamel junction showed typical organization of enamel <b>(E and insert)</b> and dentin <b>(H)</b>. Am, ameloblast; D, dentin; DEJ, dentin-enamel junction; E, enamel; Od, odontoblast; m, mitochondria; N, nucleus; OP, odontoblast processes; Pd, predentin; RER, rough endoplasmic reticulum.</p

Innervation of bioengineered teeth implanted in ICR mice.

<p>Bioengineered teeth germs were co-implanted with trigeminal ganglia in adult ICR mice <b>(A–G)</b> for 1 <b>(A–C)</b> or 2 weeks <b>(D–G).</b> Nerve fibers and blood vessels in dental pulp and peridental tissues of bioengineered tooth were analysed immunohistochemically by using specific antibodies for peripherin (red) and CD31 (green). Blood vessels were present in peridental tissues and could enter in the dental pulp and reach odontoblasts already after 1 week of implantation <b>(A–C)</b>. Nerve fibers were detected in peridental tissues, in peridendal mesenchyme <b>(F)</b> and dental pulp but never in the dental pulp after 1 week <b>(A–C)</b> or even 2 weeks <b>(D–G)</b> of implantation. D, dentin; DP, dental pulp; E, enamel; Od, odontoblasts; PDM, peridental mesenchyme; TG, trigeminal ganglia.</p