Leukocyte infiltration and activation of the NLRP3 inflammasome in white adipose tissue following thermal injury.

OBJECTIVES: Severe thermal injury is associated with extreme and prolonged inflammatory and hypermetabolic responses, resulting in significant catabolism that delays recovery or even leads to multiple organ failure and death. Burned patients exhibit many symptoms of stress-induced diabetes, including hyperglycemia, hyperinsulinemia, and hyperlipidemia. Recently, the nucleotide-binding domain, leucine-rich family (NLR), pyrin-containing 3 (NLRP3) inflammasome has received much attention as the sensor of endogenous "danger signals" and mediator of "sterile inflammation" in type II diabetes. Therefore, we investigated whether the NLRP3 inflammasome is activated in the adipose tissue of burned patients, as we hypothesize that, similar to the scenario observed in chronic diabetes, the cytokines produced by the inflammasome mediate insulin resistance and metabolic dysfunction. DESIGN: Prospective cohort study. SETTING: Ross Tilley Burn Centre & Sunnybrook Research Institute. PATIENTS: We enrolled 76 patients with burn sizes ranging from 1% to 70% total body surface area. All severely burned patients exhibited burn-induced insulin resistance and hyperglycemia. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We examined the adipose tissue of control and burned patients and found, via flow cytometry and gene expression studies, increased infiltration of leukocytes-especially macrophages-and evidence of inflammasome priming and activation. Furthermore, we observed increased levels of interleukin-1ß in the plasma of burned patients when compared to controls. CONCLUSIONS: In summary, our study is the first to show activation of the inflammasome in burned humans, and our results provide impetus for further investigation of the role of the inflammasome in burn-induced hypermetabolism and, potentially, developing novel therapies targeting this protein complex for the treatment of stress-induced diabetes.

Face allotransplantation and burns: a review.

Burns may represent one of the main indications for face allotransplantation. Severely disfigured faces featuring a devastating appearance and great functional impairments are not only seen as burn sequelae but also occur as a result of other traumatic injuries, oncological surgical resections, benign tumors (eg, neurofibromatosis), and major congenital malformations. To date, 20 human face composite tissue allotransplants have been performed with success. Despite the initial scepticism about its applicability, due mainly to ethical and technical reasons, the previous worldwide cases and their associated positive outcomes, including acceptable immunosuppressive regimens, excellent aesthetic and functional results, and good psychological acceptance by the recipient, enable the conclusion that face composite tissue allotransplantation has become another therapeutic strategy in the reconstructive surgical armamentarium, which bears special consideration when dealing with severely disfigured burned patients. The aim of this review is to describe the basics of face composite tissue allotransplantation and give an overview of some of the cases performed until now, with special attention paid to debating the pros and cons of its applicability in burn patients.

Redox regulation of macrophage migration inhibitory factor expression in rat neurons.

Macrophage migration inhibitory factor (MIF) expression is induced by angiotensin II (Ang II) in normal rat neurons and serves a negative regulatory role by blunting the chronotropic actions of this peptide. The aim here was to determine whether hydrogen peroxide (H(2)O(2)), a reactive oxygen species (ROS) that is a key intracellular mediator of the neuronal actions of Ang II, is a trigger for MIF production in neurons. Thus, we tested the effects of H(2)O(2) on MIF expression in primary neuronal cultures from newborn normotensive (Wistar Kyoto [WKY] or Sprague-Dawley [SD]) rat brain, cells that respond to Ang II by increasing MIF levels. Treatment of WKY or SD rat neuronal cultures with a non-cytotoxic concentration of H(2)O(2) elicited a significant, time-dependent increase in MIF mRNA and protein levels. Glucose oxidase, which produces H(2)O(2) via oxidation of glucose in the cell-culture medium, elicited a similar increase in neuronal MIF mRNA levels. The stimulatory action of H(2)O(2) was not apparent in neuronal cultures from spontaneously hypertensive rats (SHR), cells that fail to express increased MIF in response to Ang II. Finally, preincubation of SD rat cultures with either polyethylene glycol-catalase or actinomycin D abolished the H(2)O(2)-induced increase in MIF, suggesting that this ROS is acting intracellularly to increase transcription of the MIF gene. These results suggest the presence of a redox regulatory mechanism for induction of MIF in normotensive rat neurons.

Basal and angiotensin II-inhibited neuronal delayed-rectifier K+ current are regulated by thioredoxin.

In previous studies, we determined that macrophage migration inhibitory factor (MIF), acting intracellularly via its intrinsic thiol-protein oxidoreductase (TPOR) activity, stimulates basal neuronal delayed-rectifier K(+) current (I(Kv)) and inhibits basal and angiotensin (ANG) II-induced increases in neuronal activity. These findings are the basis for our hypothesis that MIF is a negative regulator of ANG II actions in neurons. MIF has recently been recategorized as a member of the thioredoxin (Trx) superfamily of small proteins. In the present study we have examined whether Trx influences basal and ANG II-modulated I(Kv) in an effort to determine whether the Trx superfamily can exert a general regulatory influence over neuronal activity and the actions of ANG II. Intracellular application of Trx (0.8-80 nM) into rat hypothalamic/brain stem neurons in culture increased neuronal I(Kv), as measured by voltage-clamp recordings. This effect of Trx was abolished in the presence of the TPOR inhibitor PMX 464 (800 nM). Furthermore, the mutant protein recombinant human C32S/C35S-Trx, which lacks TPOR activity, failed to alter neuronal I(Kv). Trx applied at a concentration (0.08 nM) that does not alter basal I(Kv) abolished the inhibition of neuronal I(Kv) produced by ANG II (100 nM). Given our observation that ANG II increases Trx levels in neuronal cultures, it is possible that Trx (like MIF) has a negative regulatory role over basal and ANG II-stimulated neuronal activity via modulation of I(Kv). Moreover, these data suggest that TPOR may be a general mechanism for negatively regulating neuronal activity.