Vagus nerve stimulation blocks vascular permeability following burn in both local and distal sites

Understanding the Central Nervous System Symptoms of Rotavirus: A Qualitative Review

This qualitative review on rotavirus infection and its complications in the central nervous system (CNS) aims to understand the gut–brain mechanisms that give rise to CNS driven symptoms such as vomiting, fever, feelings of sickness, convulsions, encephalitis, and encephalopathy. There is substantial evidence to indicate the involvement of the gut–brain axis in symptoms such as vomiting and diarrhea. The underlying mechanisms are, however, not rotavirus specific, they represent evolutionarily conserved survival mechanisms for protection against pathogen entry and invasion. The reviewed studies show that rotavirus can exert effects on the CNS trough nervous gut–brain communication, via the release of mediators, such as the rotavirus enterotoxin NSP4, which stimulates neighboring enterochromaffin cells in the intestine to release serotonin and activate both enteric neurons and vagal afferents to the brain. Another route to CNS effects is presented through systemic spread via lymphatic pathways, and there are indications that rotavirus RNA can, in some cases where the blood brain barrier is weakened, enter the brain and have direct CNS effects. CNS effects can also be induced indirectly as a consequence of systemic elevation of toxins, cytokines, and/or other messenger molecules. Nevertheless, there is still no definitive or consistent evidence for the underlying mechanisms of rotavirus-induced CNS complications and more in-depth studies are required in the future.

Baroreflex activation in conscious rats modulates the joint inflammatory response via sympathetic function

The baroreflex is a critical physiological mechanism controlling cardiovascular function by modulating both the sympathetic and parasympathetic activities. Here, we report that electrical activation of the baroreflex attenuates joint inflammation in experimental arthritis induced by the administration of zymosan into the femorotibial cavity. Baroreflex activation combined with lumbar sympathectomy, adrenalectomy, celiac subdiaphragmatic vagotomy or splenectomy dissected the mechanisms involved in the inflammatory modulation, highlighting the role played by sympathetic inhibition in the attenuation of joint inflammation. From the immunological standpoint, baroreflex activation attenuates neutrophil migration and the synovial levels of inflammatory cytokines including TNF, IL-1β and IL-6, but does not affect the levels of the anti-inflammatory cytokine IL-10. The anti-inflammatory effects of the baroreflex system are not mediated by IL-10, the vagus nerve, adrenal glands or the spleen, but by the inhibition of the sympathetic drive to the knee. These results reveal a novel physiological neuronal network controlling peripheral local inflammation.

PNU-282987 improves the hemodynamic parameters by alleviating vasopermeability and tissue edema in dogs subjected to a lethal burns shock

Excessive inflammation and high vasopermeability can lead to blood volume loss and tissue edema, which can affect the resuscitation and prognosis for serious burn patients. In this experiment, we investigated the effect of PNU-282987, an α7 nicotine cholinergic receptor agonist on the hemodynamic parameters and survival rate by inhibiting vasopermeability and tissue edema during the fluid resuscitation for lethal burn shock. Forty Beagle dogs with intubation of the carotid artery and jugular vein 24 hours before the injury were subjected to 50% TBSA full-thickness burns, and were randomly divided into following four groups: no resuscitation group (group NR), venous fluid resuscitation group (group R), PNU-282987 treatment group (group P), and fluid resuscitation group plus PNU-282987 group (group RP), with 10 dogs in each group. Hemodynamic variables and biochemical parameters were determined with animals in a conscious and cooperative state. The plasma volume and the vasopermeability were determined by indocyanine green and fluorescein isothiocyanate-dextran, respectively. The level of tumor necrosis factor-α and interleukin-1β in plasma, and the water content of different organs were also determined. The mean arterial pressure, cardiac output, and plasma volume of all dogs decreased significantly, and the lung extravascular water index and pulmonary vascular permeability index increased remarkably after burn. The hemodynamic parameters deteriorated continually in group N dogs, and then anuria, hyperlactacidemia, and multiple organ dysfunctions developed. The mean arterial pressure and cardiac output of dogs in group R and group RP returned to preinjury levels at 48 hours postburn. The lung extravascular water index and pulmonary vascular permeability in group R were higher than those before preinjury. The dogs in group RP were found to have a significant increase in plasma volume and urine output, and a remarkable decrease in the levels of tumor necrosis factor-α, interleukin-1α, lactic acid, and organ functions compared with those of group R (P <.05). The survival rate of RP group (100%; 10/10) was significantly higher than that of group N (0; 0/10), group P (20%; 2/10), and group R (60%; 6/10). PNU-282987 combined with intravenous fluid resuscitation significantly improved hemodynamics and the survival rate in the early period after this lethal burn shock. The mechanism may be attributable to the lowering of the level of proinflammatory mediators, amelioration of vasopermeability-induced visceral edema, less of blood volume loss, and protection of vital organs through activation of cholinergic anti-inflammatory pathway.

A pharmacologic approach to vagal nerve stimulation prevents mesenteric lymph toxicity after hemorrhagic shock

BACKGROUND

Electrical stimulation of the vagus nerve (VN) prevents gut and lung inflammation and mesenteric lymph (ML) toxicity in animal models of injury. We have previously shown that treatment with CPSI-121, a guanylhydrazone-derived compound, prevents gut barrier failure after burn injury. While the structure of CPSI-121 predicts that it will activate parasympathetic signaling, its ability to stimulate the VN is unknown. The aims of this study were to (1) measure the ability of CPSI-121 to induce VN activity, (2) determine whether CPSI-121 causes significant hemodynamic effects, and (3) further define the potential for CPSI-121 to limit the systemic inflammatory response to injury.

METHODS

Male Sprague-Dawley rats were given 1-mg/kg CPSI-121 intravenously while blood pressure, heart rate, and efferent VN electrical activity were recorded. Rats were also assigned to sham or trauma/hemorrhagic shock (T/HS). T/HS was induced by laparotomy and 60 minutes of HS (mean arterial pressure, 35 mm Hg) followed by fluid resuscitation. A separate cohort of animals received CPSI-121 after the HS phase. Gut and lung tissues were harvested for histologic analysis. Lung wet-dry ratios were also evaluated. The ability of ML to prime neutrophils was assessed by measuring in vitro oxidative burst using flow cytometry.

RESULTS

Blood pressure was not altered after treatment with CPSI-121, while heart rate decreased only slightly. Recording of efferent VN electrical activity revealed an increase in discharge rate after administration of CPSI-121. T/HS caused gut and lung injury, which were prevented in animals treated with CPSI-121 (p < 0.05). Treatment with CPSI-121 following T/HS attenuated neutrophil priming after exposure to ML (p < 0.05).

CONCLUSION

CPSI-121 causes efferent VN output and limits shock-induced gut and lung injury as well as ML toxicity. CPSI-121 is a candidate pharmacologic approach to VN stimulation aimed at limiting the inflammatory response in patients following T/HS.

The year in burns 2013

Approximately 3415 research articles were published with burns in the title, abstract, and/or keyword in 2013. We have continued to see an increase in this number; the following reviews articles selected from these by the Editor of one of the major journals (Burns) and colleagues that in their opinion are most likely to have effects on burn care treatment and understanding. As we have done before, articles were found and divided into the following topic areas: epidemiology of injury and burn prevention, wound and scar characterization, acute care and critical care, inhalation injury, infection, psychological considerations, pain and itching management, rehabilitation and long-term outcomes, and burn reconstruction. The articles are mentioned briefly with notes from the authors; readers are referred to the full papers for details.

The vagus nerve alters the pulmonary dendritic cell response to injury

BACKGROUND

We have shown previously that vagal nerve stimulation (VNS) protects against burn-induced acute lung injury (ALI). Although the mobilization and activation of immune cells is central to tissue injury caused by the systemic inflammatory response, the specific inflammatory cell populations that are modulated by VNS have yet to be fully defined. The purpose of this study was to assess whether VNS alters inflammatory cell recruitment to the lung after severe burn injury.

MATERIALS AND METHODS

Male C57BL/6 mice were subjected to 30% total body surface area steam burn with and without electrical stimulation of the right cervical vagus nerve. The relative levels of pulmonary dendritic cells (DC) and macrophages were compared at 4 h versus 24 h after burn injury. Lung tissue injury was characterized by histology to assess changes in lung architecture, and measure the protein levels of interleukin 6 and transforming growth factor-β1.

RESULTS

Severe burn caused an increase in pulmonary DC recruitment at 4 h after injury that persisted at 24 h after severe burn, whereas there was no change in the number of pulmonary macrophages. In contrast, VNS limited the burn-induced recruitment of pulmonary DC. VNS prevented histologic lung injury and attenuated the release of interleukin 6 and transforming growth factor-β1 in the lung after burn injury.

CONCLUSIONS

VNS is an effective method to limit pulmonary DC recruitment to the lung and prevent ALI after burn injury. Identifying strategies to limit inflammatory cell recruitment to the lung may have clinical utility in preventing ALI in severely burned patients.

NDP-MSH inhibits neutrophil migration through nicotinic and adrenergic receptors in experimental peritonitis

Melanocortin is a potent anti-inflammatory molecule. However, little is known about the effect of melanocortin on acute inflammatory processes such as neutrophil migration. In the present study, we investigated the ability of [Nle4, D-Phe7]-melanocyte-stimulating hormone (NDP-MSH), a semisynthetic melanocortin compound, in the inhibition of neutrophil migration in carrageenin-induced peritonitis model. Herein, subcutaneous pretreatment with NDP-MSH decreased neutrophil trafficking in the peritoneal cavity in a dose-dependent manner. NDP-MSH inhibited vascular leakage, leukocyte rolling, and adhesion and reduced peritoneal macrophage inflammatory protein 2, but not TNF-alpha, IL-1beta, IL-10, and keratinocyte-derived chemokine production. In addition, the effect on neutrophil migration was reverted by the pretreatment with both propranolol (a nonselective beta-adrenergic antagonist) and mecamylamine (a nonselective nicotinic antagonist) but not by splenectomy surgery. Moreover, NDP-MSH intracerebroventricular administration inhibited neutrophil migration, indicating participation of the central nervous system. Our results propose that the NDP-MSH effect may be due to a spleen-independent neuro-immune pathway that efficiently regulates excessive neutrophil recruitment to tissues.