Role of vasoactive intestinal polypeptide in burn-induced oedema formation

Burn injury induces elevated inflammatory traffic: the role of NF-κB

A burn insult generally sustains a hypovolemic shock due to a significant loss of plasma from the vessels. The burn injury triggers the release of various mediators, such as reactive oxygen species (ROS), cytokines, and inflammatory mediators. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), stemming from foreign microbial discharge and damaged tissue or necrotic cells from the burn-injured site, enter the systemic circulation, activate toll-like receptors (TLRs), and trigger the excessive secretion of cytokines and inflammatory mediators. Inflammation plays a vital role in remodeling an injured tissue, detoxifying toxins, and helps in the healing process. A transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), contributes to a variety of physiological and pathological conditions, including immune response, cell death, cell survival, and inflammatory processes. During the pathogenesis of a burn wound, upregulation of various cytokines and growth factors lead to undesirable tissue inflammation. Thus, NF-κB, a dominant moderator of inflammation, needs to be altered to prove beneficial to the treatment of burns or other inflammation-associated diseases. This review addresses the relationship between NF-κB and elevated inflammation in a burn condition that could potentially be altered to induce an early wound-healing mechanism of burn wounds.

The use of botulinum toxin in the management of burns itching: preliminary results

Itching is a common and well recognised problem following burns. As the underlying pathways involved in burns itch have been identified, different pharmacological agents have been introduced to improve the effectiveness of management regimes. We present preliminary data from an on-going study in the use of botulinum toxin as a novel agent in the treatment of this problem.

METHOD

Patients with recalcitrant itching secondary to burns treated with Botox(©) were identified. Data pertaining to burn size, depth and management were recorded. The delay in the onset of the itch, its severity and the speed and duration of any improvement in symptoms were also noted.

RESULTS

10 patients were identified. 1 patient was excluded. Average follow-up was 11.3 months. All patients had deep partial thickness to full thickness burns. Eight patients underwent grafting. The average burn was 24% TBSA. 87.5% of patients rated their burns itch as being severe (>7 on the pain scale). Following the administration of Botox(©) this fell to 0 out of 10 at 4 weeks. The average duration of the symptom free period was nine months (range 3-18 months).

CONCLUSION

Botox(©) can successfully be used to treat burns itch that are resistant to conventional therapies.

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

Recent studies have shown that vagus nerve stimulation (VNS) can block the burn-induced systemic inflammatory response (SIRS). In this study we examined the potential for VNS to modulate vascular permeability (VP) in local sites (i.e. skin) and in secondary sites (i.e. lung) following burn. In a 30% total body surface area burn model, VP was measured using intravascular fluorescent dextran for quantification of the VP response in skin and lung. A peak in VP of the skin was observed 24h post-burn injury, that was blocked by VNS. Moreover, in the lung, VNS led to a reduction in burn-induced VP compared to sham-treated animals subjected to burn alone. The protective effects of VNS in this model were independent of the spleen, suggesting that the spleen was not a direct mediator of VNS. These studies identify a role for VNS in the regulation of VP in burns, with the translational potential of attenuating lung complications following burn.

Update on pruritic mechanisms of hypertrophic scars in postburn patients: the potential role of opioids and their receptors

Although itching (or pruritus) in a scar is a very common and distressing symptom and is increasingly being recognized as a significant obstacle in burn rehabilitation, the exact mechanisms underlying this symptom have not been elucidated; hence, a reliable therapy has not been established. Recent findings have suggested that itching caused by inflammatory dermatosis can be reduced by antihistamines, but histamine antagonists cannot block all types of pruritus (eg, neuropathic itch). This indicates the presence of a histamine-independent pathway for itch. Itch or pruritus may also be evoked by direct activation of opioid receptors, which have recently been identified in the skin. This article aims to assess the current state of knowledge regarding the role of opioids in the generation of itch in hypertrophic scars in postburn patients. To this end, the authors have reviewed the relevant literature and present some clinical data. The authors hope that this review will form the basis for future research to elucidate the mechanism and treatment of itch.

Scratching the surface--Managing the itch associated with burns: a review of current knowledge

The problems of itch in burns patients are well recognised, however none of the current standard therapies are very effective. The standard therapies include: antihistamines which are only effective in about 20% of patients and emollients which have limited effects. We review the current literature on the molecular mechanisms of itch and neuronal itch pathways, which supports the predictable lack of effect of anti-histamines. The published studies on therapeutic options to treat itch in burns are discussed and in addition we review the work on the treatment of itch in other pathological states. Finally a treatment algorithm is proposed stratifying possible therapeutic options to assist in the management of burns patients distressed by intractable itch.

Effects of full-thickness burns on nociceptor sensitization in anesthetized rats

Burn-induced pain is often inadequately managed and its mechanisms, both peripheral and central, are poorly understood. To examine peripheral mechanisms, the effects of full-thickness burns on individual nociceptive fibers in sural nerve of anesthetized rats were studied. Additionally, the study investigated whether topical post-burn treatment with the mu-opioid receptor agonist loperamide ameliorated burn-induced pathologies. Receptive field (RF) properties of C-fibers were determined for 4h before and after producing burns. Burns caused profound tissue damage with edema extending beyond the injury site. Injury located within or proximal to RFs of nociceptors caused rapid decreases in mechanical responsiveness or complete desensitization at the original test site. However, post-burn, RF size frequently grew to include areas of newly sensitized skin. Transient or prolonged periods of ectopic activity was recorded from some nociceptors; this was most prevalent in fibers with RFs proximal to the injury site where burn induced background firing in 60% of the population. In most cases, loperamide significantly increased mechanical thresholds, prevented sensitization of uninjured skin, and reduced discharge.These data indicate that full-thickness burns activate and/or sensitize C-nociceptors, thus probably leading to pain. As loperamide ameliorates nociceptor activation and sensitization, it is an appropriate candidate for burn pain management.