Effects of dietary glutamine supplementation on immune cell polarization and muscle regeneration in diabetic mice with limb ischemia.

PURPOSE: Diabetes is a chronic inflammatory disorder resulting in endothelial dysfunction which contributes to peripheral arterial disease and limb ischemia. Leukocytes play critical roles in vascular and tissue remodelling after ischemia. This study investigated the effects of dietary glutamine (GLN) supplementation on immune cell polarization in diabetic mice subjected to limb ischemia. METHODS: Diabetes was induced by an intraperitoneal injection of streptozotocin for 5 consecutive days in C57BL/6J mice. Diabetic mice were fed the AIN-93 diet or an AIN-93 diet in which a part of the casein was replaced by GLN. After 3 weeks of the dietary intervention, mice were subjected to unilateral femoral artery ligation to induce limb ischemia. RESULTS: GLN supplementation enhanced the proportion of anti-inflammatory monocytes and regulatory T cells in the blood. Expression of C-C motif chemokine receptor 5 by activated CD4+ T cells was promoted and prolonged in the GLN-supplemented group. GLN downregulated the percentage of M1 macrophages in muscle tissues which was correlated with lower levels of C-C motif chemokine ligand 2 in plasma. The muscle M1/M2 ratio was also reduced in the GLN group. Gene expression of interleukin-6 was suppressed by GLN supplementation, while expression levels of the peroxisome proliferator-activated receptor γ and myogenic differentiation 1 genes were elevated in post-ischemic muscles. Histological findings also indicated that muscle regeneration was accelerated in the GLN group. CONCLUSIONS: GLN supplementation in diabetic mice may exert more-balanced polarization of CD4+ T cells, monocytes, and macrophages, thus attenuating inflammatory responses and contributing to muscle regeneration after limb ischemia.

Neuro-immune lessons from an annelid: The medicinal leech.

An important question that remains unanswered is how the vertebrate neuroimmune system can be both friend and foe to the damaged nervous tissue. Some of the difficulty in obtaining responses in mammals probably lies in the conflation in the central nervous system (CNS), of the innate and adaptive immune responses, which makes the vertebrate neuroimmune response quite complex and difficult to dissect. An alternative strategy for understanding the relation between neural immunity and neural repair is to study an animal devoid of adaptive immunity and whose CNS is well described and regeneration competent. The medicinal leech offers such opportunity. If the nerve cord of this annelid is crushed or partially cut, axons grow across the lesion and conduction of signals through the damaged region is restored within a few days, even when the nerve cord is removed from the animal and maintained in culture. When the mammalian spinal cord is injured, regeneration of normal connections is more or less successful and implies multiple events that still remain difficult to resolve. Interestingly, the regenerative process of the leech lesioned nerve cord is even more successful under septic than under sterile conditions suggesting that a controlled initiation of an infectious response may be a critical event for the regeneration of normal CNS functions in the leech. Here are reviewed and discussed data explaining how the leech nerve cord sensu stricto (i.e. excluding microglia and infiltrated blood cells) recognizes and responds to microbes and mechanical damages.

Inflammation and regeneration in the dentin-pulp complex: a double-edged sword.

Dental tissue infection and disease result in acute and chronic activation of the innate immune response, which is mediated by molecular and cellular signaling. Different cell types within the dentin-pulp complex are able to detect invading bacteria at all stages of the infection. Indeed, at relatively early disease stages, odontoblasts will respond to bacterial components, and as the disease progresses, core pulpal cells including fibroblasts, stems cells, endothelial cells, and immune cells will become involved. Pattern recognition receptors, such as Toll-like receptors expressed on these cell types, are responsible for detecting bacterial components, and their ligand binding leads to the activation of the nuclear factor-kappa B and p38 mitogen-activated protein (MAP) kinase intracellular signaling cascades. Subsequent nuclear translocation of the transcription factor subunits from these pathways will lead to proinflammatory mediator expression, including increases in cytokines and chemokines, which trigger host cellular defense mechanisms. The complex molecular signaling will result in the recruitment of immune system cells targeted at combating the invading microbes; however, the trafficking and antibacterial activity of these cells can lead to collateral tissue damage. Recent evidence suggests that if inflammation is resolved relatively low levels of proinflammatory mediators may promote tissue repair, whereas if chronic inflammation ensues repair mechanisms become inhibited. Thus, the effects of mediators are temporal context dependent. Although containment and removal of the infection are keys to enable dental tissue repair, it is feasible that the development of anti-inflammatory and immunomodulatory approaches, based on molecular, epigenetic, and photobiomodulatory technologies, may also be beneficial for future endodontic treatments.

PVY-resistant transgenic potato plants expressing an anti-NIa protein scFv antibody.

A synthetic gene encoding a single chain Fv fragment of an antibody directed against the nuclear inclusion a (NIa) protein of potato virus Y (PVY) was used to transform two commercial potato cultivars (Claustar and BF15). The NIa protease forms the nuclear inclusion body A and acts as the major protease in the cleavage of the viral polyprotein into functional proteins. Immunoblot analysis showed that most of the resulting transgenic plants accumulate high levels of the transgenic protein. Furthermore, a majority of the selected transgenic lines showed an efficient and complete protection against the challenge virus after mechanical inoculation with PVYO strain. Two transgenic lines showed an incomplete resistance with delayed appearance of symptoms accompanied by low virus titers, whereas one line developed symptoms during the first days after inoculation but recovered rapidly, leading to a low virus accumulation rate. These results confirm that expression of scFv antibody is able to inhibit a crucial step in the virus multiplication, such as polyprotein cleavage is a powerful strategy for engineered virus resistance. It can lead to a complete resistance that was not obtained previously by expression of scFv directed against the viral coat protein.

Pulmonary edema fluid from patients with acute lung injury augments in vitro alveolar epithelial repair by an IL-1beta-dependent mechanism.

Efficient alveolar epithelial repair is crucial for the restoration of the injured alveolar epithelial barrier in patients with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). We hypothesized that pulmonary edema fluid from patients with ALI /ARDS would inhibit alveolar epithelial repair as measured in an in vitro epithelial wound-repair model using the human alveolar epithelial-like cell line A549. In contrast to our initial hypothesis, pulmonary edema fluid from patients with ALI/ARDS increased alveolar epithelial repair by 33 +/- 3% compared with pooled plasma from healthy donors (p < 0.01). By contrast, the plasma and the pulmonary edema fluid from patients with hydrostatic pulmonary edema, and the plasma from patients with ALI/ARDS had similar effects on epithelial repair as pooled plasma from healthy donors. Inhibition of interleukin-1beta (IL-1beta) activity by IL-1 receptor antagonist reduced alveolar epithelial repair induced by ALI/ARDS edema fluid by 46 +/- 4% (p < 0.001), indicating that IL-1beta contributed significantly to the increased epithelial repair. In summary, pulmonary edema fluid collected early in the course of ALI/ARDS increased alveolar epithelial repair in vitro by an IL-1beta-dependent mechanism. These data demonstrate a novel role for IL-1beta in patients with ALI/ARDS, indicating that IL-1beta may promote repair of the injured alveolar epithelium.