The Effect of Botulinum Toxin A on Ischemia-Reperfusion Injury in a Rat Model

The Effect of Botulinum Toxin A on the NADPH Oxidase System and Ischemia-Reperfusion Injury

BACKGROUND

Despite the increasing popularity of various materials for ischemia-reperfusion (I/R) injury mitigation, research on botulinum toxin type A (BoNTA) remains limited. This study assesses BoNTA's efficacy in protecting flaps from I/R injury by inhibiting the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system and reducing reactive oxygen species (ROS) production.

METHODS

Seventy-six Sprague-Dawley rats were studied. We examined the effects of BoNTA on superoxide production in four rats using a lucigenin-enhanced chemiluminescence assay (LECL). Another group of 60 rats had their superficial inferior epigastric artery (SIEA) flaps treated with either BoNTA or saline and clamped for 0, 1, and 4 hours before reperfusion. Flap survival and histological outcomes were assessed five days post-operation. ROS production in SIEA flaps and femoral vessels was analyzed in 12 additional rats, post-I/R injury.

RESULTS

The LECL results showed that the BoNTA group had significantly lower superoxide production compared to controls, with notable reductions at 4 hours. While no significant differences were noted at the 0 and 1-hour marks, the 4-hour mark showed significant protective effects in BoNTA-treated groups. The survival rate was 90% for BoNTA-treated rats versus 60% for controls ( P = 0.028). Significant reductions in ROS were also observed in the 4-hour I/R group.

CONCLUSIONS

BoNTA effectively protects against I/R injury by inhibiting the NADPH oxidase system and reducing ROS levels. These results support further investigation into the specific mechanisms of NADPH oxidase inhibition by BoNTA and its potential clinical applications, given its safety profile.

CLINICAL RELEVANCE STATEMENT

The findings from the present study are expected to provide a basis for clinical studies regarding this use of BoNTA.

Effect of botulinum toxin-A injection applied to the mentalis muscle on free gingival graft operation: A retrospective study

OBJECTIVE

The purpose of this retrospective study was to investigate the effects of Botulinum Toxin-A (BTX-A) injection into the mentalis muscle on the free gingival graft (FGG).

MATERIALS AND METHODS

Forty patients with keratinized gingiva insufficiency and Cairo's RT 2 gingival recession (formerly classified as Miller class III) in their mandibular central incisors were randomly divided into two groups: FGG and FGG + BTX. Plaque index (PI), gingival index (GI), probing pocket depth (PPD), keratinized gingiva width (KGW), attached gingiva width (AGW), clinical attachment level (CAL), gingival thickness (GT), gingival recession amount (GRA), gingival recession width (GRW), and root closure percentage (RCP%) parameters were measured at baseline and at first, third, and sixth months after the operation.

RESULTS

There was no difference in PI, GI, and PPD levels in both groups (p > 0.05). While the change in GT and RCP% levels were found to be statistically significantly higher at FGG + BTX group than FGG group, the change in GRW and CAL levels were statistically significantly lower (p < 0.05).

CONCLUSION

The findings of this study indicate that BTX-A injection applied to the mentalis muscle after FGG operation may have positive effects in terms of KGW, AGW, GT, RCP%, GRW, and CAL parameters.

CLINICAL SIGNIFICANCE

As a result of the fact that BTX-A injection into the mentalis muscle contributed to the nutrition and immobility of FGG, positive developments were obtained in terms of clinical periodontal parameters. BTX-A injection into the mentalis muscle may be an alternative method that increases the success rate of Cairo's RT 2 gingival recession.

Current Status of Experimental Animal Skin Flap Models: Ischemic Preconditioning and Molecular Factors

Skin flaps are necessary in plastic and reconstructive surgery for the removal of skin cancer, wounds, and ulcers. A skin flap is a portion of skin with its own blood supply that is partially separated from its original position and moved from one place to another. The use of skin flaps is often accompanied by cell necrosis or apoptosis due to ischemia-reperfusion (I/R) injury. Proinflammatory cytokines, such as nuclear factor kappa B (NF-κB), inhibitor of kappa B (IκB), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and oxygen free radicals are known causative agents of cell necrosis and apoptosis. To prevent I/R injury, many investigators have suggested the inhibition of proinflammatory cytokines, stem-cell therapies, and drug-based therapies. Ischemic preconditioning (IPC) is a strategy used to prevent I/R injury. IPC is an experimental technique that uses short-term repetition of occlusion and reperfusion to adapt the area to the loss of blood supply. IPC can prevent I/R injury by inhibiting proinflammatory cytokine activity. Various stem cell applications have been studied to facilitate flap survival and promote angiogenesis and vascularization in animal models. The possibility of constructing tissue engineered flaps has also been investigated. Although numerous animal studies have been published, clinical data with regard to IPC in flap reconstruction have never been reported. In this study, we present various experimental skin flap methods, IPC methods, and methods utilizing molecular factors associated with IPC.

Effect of botulinum toxin type A on flap surgery in animal models: a systematic review and meta-analysis

Flaps are common technical choices in aesthetic and reconstructive surgeries. However, the poor flap survival rate remains to be a difficult issue that troubles plastic surgeon. Recent research evidence supports that the use of Botulinum toxin type A (BTXA) can increase the flap survival rate. For verification, the present study was carried out to evaluate the effect of BTXA on flap surgery. Eight databases (PubMed, Cochrane Library, Ovid, Web of Science, Embase, Scopus, CBM, CNKI and WANFANG database) were searched for related published literature up to September 2020. A meta-analysis was then conducted to compare the effect of using BTXA with that of using saline or no treatment in flap surgery. Seventeen studies with a total of 565 animals were finally included in this review after strict exclusion and inclusion. Compared with saline/no treatment + flap group, BTXA + flap group showed a significantly higher flap tissue survival rate (mean difference [MD] 15.55, p < 0.00001), blood flow (standardized mean difference [SMD] 1.97, p < 0.00001) and vascular endothelial growth factor (VEGF) expression (at mRNA level: SMD 6.01, p = 0.02; at protein level: SMD 3.35, p < 0.00001). BTXA combined with flap surgery may have a positive effect on improving the flap tissue survival rate, blood flow of flaps and VEGF expression. Besides, the timing of BTXA injection may be an important factor for exerting its effect on flap surgery.

Effects of Botulinum Toxin Type A on Microvessels in Hypertrophic Scar Models on Rabbit Ears

Background

Although Botulinum Toxin Type A (BTXA) has been applied to scar prevention and treatment, the mechanisms still require further exploration.

Objective

To investigate the effects of BTXA on microvessels in the hypertrophic scar models on rabbit ears.

Methods

Eight big-eared New Zealand rabbits (males or females) were selected to establish scar models. One ear of each rabbit (4 models in each ear) was selected randomly to be injected with BTXA immediately after modeling and included in the treated group, while the opposite ear was untreated and included in the control group. The growth of scars in each group was observed and recorded, and 4 rabbits were sacrificed on days 30 and 45 after modeling. Then, scar height was measured by hematoxylin-eosin (HE) staining, vascular endothelial growth factor (VEGF) expression was detected by immunohistochemical (IHC) testing, and microvessel density (MVD) was calculated based on CD34 (human hematopoietic progenitor cell antigen).

Results

The wounds in each group were well healed and free from infection or necrosis. On days 30 and 45, the scar height, MVD value, and VEGF expression in the treated group were lower than those in the control group (P < 0.05). For the treated group, the above indicators on day 45 were lower than on day 30 (P > 0.05). Besides, there was a positive correlation between the MVD value and the VEGF expression in the treated group (P < 0.05).

Conclusion

The injection of BTXA immediately after modeling inhibits VEGF expression and reduces angiogenesis, thereby inhibiting hypertrophic scar formation.

Protective effect of luteolin on skin ischemia-reperfusion injury through an AKT-dependent mechanism

Cutaneous ischemia-reperfusion (I/R) injury is one of the most crucial problems in flap surgery, which affects the survival of the skin flap and patient prognosis, luteolin, a plant derived flavonoid, has previously been shown to exert a variety of beneficial effects for reducing I/R injury in several organs. The aim of the present study was to evaluate the anti-inflammatory and anti-oxidative stress effects of luteolin on cutaneous I/R injury. The in vitro study were performed using a permanent human immortalized epidermal keratinocyte cell line (HaCaT), cells were cultured in the presence of luteolin and were then treated with hydrogen peroxide, the cell viability, mitochondrial membrane potential and the cell survival/apoptosis related signaling pathway activation were assessed to investigate the cytoprotective effects of luteolin. For in vivo experiments, skin flap I/R injury animal model was established in Sprague-Dawley rats, by measuring the area of flap survival, analyzing the expression of pro-inflammatory cytokine and evaluation of the histological changes in the skin tissue, the protective effects of luteolin on skin I/R injury were investigated. The function of protein kinase B (AKT) and heme oxygenase-1 (HO-1) activation on luteolin mediated I/R injury protection was assessed by administration of phosphoinositide-3-kinase/AKT inhibitor LY294002 and HO-1 inhibitor ZNPP. The results showed that luteolin treatment significantly increased the viability of HaCaT cells upon exposure to hydrogen peroxide, and the administration of luteolin in vivo significantly improved skin flap survival in the I/R injury rat model. The mechanisms underlying these beneficial effects included increased phosphoinositide-3-kinase/protein kinase B activation, improved expression of antioxidant enzyme, and scavenging the cytotoxic effects of reactive oxygen species (ROS). Taken together, the results suggested that luteolin preconditioning yielded significant protection against cutaneous I/R injury by protecting skin keratinocytes from ROS-induced damage.

Botulinum toxin A increases allograft tolerance in an experimental transplantation model: a preliminary study

Identifying novel and safe immunosuppressants is of crucial importance. Recently, there have been several studies revealing that botulinum toxin A (BoTA) significantly alleviates ischemia–reperfusion injuries. Emerging evidence shows that ischemia–reperfusion injuries contribute to innate immune activation, promoting rejection, and inhibiting tolerance. Therefore, we hypothesized that a pretreatment with BoTA might decrease allograft rejection in a rat transplantation model. Twenty-four Lewis (LEW) rats were randomly assigned into two groups consisting of 12 rats each, depending on whether skin allograft was performed after pretreatment with BoTA (BoTA group) or with normal saline (control group). The experimental group was pretreated with a subcutaneous injection of BoTA (10 IU), while the control group was pretreated with normal saline 5 days prior to surgery. The donor Brown–Norway (BN) rat dorsal skin was subsequently grafted to the recipient LEW rats. The recipient wounds, measuring 2 cm × 2 cm, were made via dorsal skin excision through the panniculus carnosus. The donor skins of the same dimensions were obtained and transplanted on to the wounds and sutured with 4-0 nylon sutures. Mean graft survival time was measured in both groups. Quantitative reverse-transcriptase PCR and Western blotting were performed to evaluate the gene/protein expression of CD4 and VEGF. The mean graft survival time in the BoTA group was significantly longer than that of the control group (P=0.004). The relative mRNA and protein expression of CD4 was significantly lower in the BoTA group (P<0.001), while the relative mRNA and protein expression of VEGF was significantly higher in the BoTA group (P<0.001). In conclusion, our results show that BoTA prolongs the survival of skin allografts in a rat transplantation model.