Mitogenic bovine whey extract modulates matrix metalloproteinase-2, -9, and tissue inhibitor of matrix metalloproteinase-2 levels in chronic leg ulcers

Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that up to 1% of people in high-income countries suffer from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 22% of ulcers). Treatment of arterial leg ulcers is directed towards correcting poor arterial blood supply, for example by correcting arterial blockages (either surgically or pharmaceutically). If the blood supply has been restored, these arterial ulcers can heal following principles of good wound-care. Dressings and topical agents make up a part of good wound-care for arterial ulcers, but there are many products available, and it is unclear what impact these have on ulcer healing. This is the third update of a review first published in 2003.

OBJECTIVES

To determine whether topical agents and wound dressings affect healing in arterial ulcers. To compare healing rates and patient-centred outcomes between wound dressings and topical agents.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature and Allied and Complementary Medicine databases, the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials register to 28 January 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs), or controlled clinical trials (CCTs) evaluating dressings and topical agents in the treatment of arterial leg ulcers were eligible for inclusion. We included participants with arterial leg ulcers irrespective of method of diagnosis. Trials that included participants with mixed arterio-venous disease and diabetes were eligible for inclusion if they presented results separately for the different groups. All wound dressings and topical agents were eligible for inclusion in this review. We excluded trials which did not report on at least one of the primary outcomes (time to healing, proportion completely healed, or change in ulcer area).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted information on the participants' characteristics, the interventions, and outcomes using a standardised data extraction form. Review authors resolved any disagreements through discussion. We presented the data narratively due to differences in the included trials. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

Two trials met the inclusion criteria. One compared 2% ketanserin ointment in polyethylene glycol (PEG) with PEG alone, used twice a day by 40 participants with arterial leg ulcers, for eight weeks or until healing, whichever was sooner. One compared topical application of blood-derived concentrated growth factor (CGF) with standard dressing (polyurethane film or foam); both applied weekly for six weeks by 61 participants with non-healing ulcers (venous, diabetic arterial, neuropathic, traumatic, or vasculitic). Both trials were small, reported results inadequately, and were of low methodological quality. Short follow-up times (six and eight weeks) meant it would be difficult to capture sufficient healing events to allow us to make comparisons between treatments. One trial demonstrated accelerated wound healing in the ketanserin group compared with the control group. In the trial that compared CGF with standard dressings, the number of participants with diabetic arterial ulcers were only reported in the CGF group (9/31), and the number of participants with diabetic arterial ulcers and their data were not reported separately for the standard dressing group. In the CGF group, 66.6% (6/9) of diabetic arterial ulcers showed more than a 50% decrease in ulcer size compared to 6.7% (2/30) of non-healing ulcers treated with standard dressing. We assessed this as very-low certainty evidence due to the small number of studies and arterial ulcer participants, inadequate reporting of methodology and data, and short follow-up period. Only one trial reported side effects (complications), stating that no participant experienced these during follow-up (six weeks, low-certainty evidence). It should also be noted that ketanserin is not licensed in all countries for use in humans. Neither study reported time to ulcer healing, patient satisfaction or quality of life.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers.

Exudates absorption and proteases trapping in venous leg ulcers

OBJECTIVE

In venous leg ulcer (VLU), the impaired healing has been shown to be associated with excessive levels of protease activities such as matrix metalloproteinases (MMPs) and elastases found in exudates. The present study focused on exudates absorption and proteases trapping capacity of a new generation of polyacrylate superabsorbent, Tegaderm superabsorber (TS), compared with a traditional dressing such as Zetuvit.

METHOD

We studied the proteases implicated in VLU (MMP-1, MMP-2, MMP-9 and PMN elastase). Absorption was tested using an artificial exudate like fluid, over 30 minutes. The protein trapping ability was obtained using ELISA assays (enzyme-linked immunosorbent assay) to determine the amount retained by the dressings from spiked fluid samples.

RESULTS

TS had a higher exudate absorption capacity (72.8±1.7%) compared with the standard dressing (36.5±1.6%), and was also able to trap and retain proteases while the standard dressing released them. The difference was shown to be much larger for MMP-2 and PMN elastase.

CONCLUSION

In our knowledge, this is the first comparative in vitro study evaluating absorption capacity as well as protease trapping capacity of a polyacrylate dressing for the four most implicated proteases in VLU. TS could be an appropriate alternative to improve the management of VLU by trapping MMPs and PMN elastse with a particularly high affinity for MMP-2 and PMN elastase.

Protease activity as a prognostic factor for wound healing in venous leg ulcers

BACKGROUND

Venous leg ulcers (VLUs) are a common type of complex wound that have a negative impact on people's lives and incur high costs for health services and society. It has been suggested that prolonged high levels of protease activity in the later stages of the healing of chronic wounds may be associated with delayed healing. Protease modulating treatments have been developed which seek to modulate protease activity and thereby promote healing in chronic wounds.

OBJECTIVES

To determine whether protease activity is an independent prognostic factor for the healing of venous leg ulcers.

SEARCH METHODS

In February 2018, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid Embase and CINAHL.

SELECTION CRITERIA

We included prospective and retrospective longitudinal studies with any follow-up period that recruited people with VLUs and investigated whether protease activity in wound fluid was associated with future healing of VLUs. We included randomised controlled trials (RCTs) analysed as cohort studies, provided interventions were taken into account in the analysis, and case-control studies if there were no available cohort studies. We also included prediction model studies provided they reported separately associations of individual prognostic factors (protease activity) with healing. Studies of any type of protease or combination of proteases were eligible, including proteases from bacteria, and the prognostic factor could be examined as a continuous or categorical variable; any cut-off point was permitted. The primary outcomes were time to healing (survival analysis) and the proportion of people with ulcers completely healed; the secondary outcome was change in ulcer size/rate of wound closure. We extracted unadjusted (simple) and adjusted (multivariable) associations between the prognostic factor and healing.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion at each stage, and undertook data extraction, assessment of risk of bias and GRADE assessment. We collected association statistics where available. No study reported adjusted analyses: instead we collected unadjusted results or calculated association measures from raw data. We calculated risk ratios when both outcome and prognostic factor were dichotomous variables. When the prognostic factor was reported as continuous data and healing outcomes were dichotomous, we either performed regression analysis or analysed the impact of healing on protease levels, analysing as the standardised mean difference. When both prognostic factor and outcome were continuous data, we reported correlation coefficients or calculated them from individual participant data.We displayed all results on forest plots to give an overall visual representation. We planned to conduct meta-analyses where this was appropriate, otherwise we summarised narratively.

MAIN RESULTS

We included 19 studies comprising 21 cohorts involving 646 participants. Only 11 studies (13 cohorts, 522 participants) had data available for analysis. Of these, five were prospective cohort studies, four were RCTs and two had a type of case-control design. Follow-up time ranged from four to 36 weeks. Studies covered 10 different matrix metalloproteases (MMPs) and two serine proteases (human neutrophil elastase and urokinase-type plasminogen activators). Two studies recorded complete healing as an outcome; other studies recorded partial healing measures. There was clinical and methodological heterogeneity across studies; for example, in the definition of healing, the type of protease and its measurement, the distribution of active and bound protease species, the types of treatment and the reporting of results. Therefore, meta-analysis was not performed. No study had conducted multivariable analyses and all included evidence was of very low certainty because of the lack of adjustment for confounders, the high risk of bias for all studies except one, imprecision around the measures of association and inconsistency in the direction of association. Collectively the research indicated complete uncertainty as to the association between protease activity and VLU healing.

AUTHORS' CONCLUSIONS

This review identified very low validity evidence regarding any association between protease activity and VLU healing and there is complete uncertainty regarding the relationship. The review offers information for both future research and systematic review methodology.

Heat delays skin wound healing in mice

In vivo studies have shown that the combination of infrared radiation (IR) and visible light (VIS) is responsible for the activation of metaloproteinases, causing matrix degradation and damage to healthy skin. However, the role of heat originating from the VIS spectrum on wound healing remains poorly understood. Our objective was to investigate the macroscopic, microscopic and biochemical effects of heat induced by visible light on cutaneous wound healing in mice. Male mice were anesthetized, subjected to a cutaneous excisional wound and divided into two groups ( n = 10/group) exposed to 23℃ or 43℃ in a thermal chamber for 30 min every other day, for 13 days. On day 14, the animals were sacrificed, and their lesions were processed for histochemistry, immunohistochemistry and protein expression analysis. The wound area was 42% greater 11 days ( p < 0.01) and 29% greater 14 days ( p < 0.001) after wounding in the 43℃ group than in the 23℃ group. The 43℃ group presented a lower (17%) percentage of reepithelialized wounds ( p < 0.001) 14 days after wounding. The length of the epidermal gap was greater in the 43℃ group ( p < 0.01). The volume density of myofibroblasts and the number of F4/80-positive macrophages was greater in the 43℃ group ( p < 0.05). The 43℃ group showed increased protein expression of type III collagen ( p < 0.001), decreased protein expression of type I collagen ( p < 0.05), increased MMP-1 expression ( p < 0.05), and decreased MMP-2 activity ( p < 0.001). The protein expression of fibrillin-1 ( p < 0.001), MMP-12 ( p < 0.05), TGF-β 1/2/3 ( p < 0.01) and ERK activation ( p < 0.05) was increased in the 43℃ group. Our results suggest that heat delays the stages of wound healing in mice.

A 'test and treat' strategy for elevated wound protease activity for healing in venous leg ulcers

BACKGROUND

Venous leg ulcers are a common and recurring type of complex wound. They can be painful, malodorous, prone to infection and slow to heal. Standard treatment includes compression therapy and a dressing. The use of protease-modulating treatments for venous leg ulcers is increasing. These treatments are based on some evidence that a proportion of slow to heal ulcers have elevated protease activity in the wound. Point-of-care tests which aim to detect elevated protease activity are now available. A 'test and treat' strategy involves testing for elevated proteases and then using protease-modulating treatments in ulcers which show elevated protease levels.

OBJECTIVES

To determine the effects on venous leg ulcer healing of a 'test and treat' strategy involving detection of high levels of wound protease activity and treatment with protease-modulating therapies, compared with alternative treatment strategies such as using the same treatment for all participants or using a different method of treatment selection.

SEARCH METHODS

We searched the following electronic databases to identify reports of relevant randomised clinical trials: The Cochrane Wounds Group Specialised Register (January 2016), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) Issue 12, 2015); Ovid MEDLINE (1946 to January 2016); Ovid MEDLINE (In-Process & Other Non-Indexed Citations January 2016); Ovid EMBASE (1974 to January 2016); EBSCO CINAHL (1937 to January 2016). We also searched three clinical trials registers, reference lists and the websites of regulatory agencies. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

Published or unpublished RCTs which assessed a test and treat strategy for elevated protease activity in venous leg ulcers in adults compared with an alternative treatment strategy. The test and treat strategy needed to be the only systematic difference between the groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection; we planned that two authors would also assess risk of bias and extract data.

MAIN RESULTS

We did not identify any studies which met the inclusion criteria for this review. We identified one ongoing study; it was unclear whether this would be eligible for inclusion.

AUTHORS' CONCLUSIONS

Currently there is no randomised evidence on the impact of a test and treat policy for protease levels on outcomes in people with venous leg ulcers.

Psychological stress-induced catecholamines accelerates cutaneous aging in mice

Psychological stress may be an important extrinsic factor which influences aging process. However, neither study demonstrated the mechanism by which chronic stress participates in skin aging. Aim of this study was to investigate the effects of chronic psychological stress on mice skin. Mice were daily submitted to rotational stress, for 28 days, until euthanasia. After 28 days, mice were killed and normal skin was analyzed. Macroscopically, dorsum skin of chronically stressed mice presented more wrinkled when compared to that of nonstressed mice. In mice skin, chronic stress increased lipid peroxidation, carbonyl protein content, nitrotyrosine levels, neutrophil infiltration, neutrophil elastase, tissue inhibitor of metalloproteinase-1 and metalloproteinase-8 levels. Nevertheless, chronic stress reduced dermis thickness, collagen type I, fibrilin-1 and elastin protein levels in mice skin. In in vitro assays, murine skin fibroblasts were exposed to elevated epinephrine levels plus inhibitors of reactive oxygen species (ROS) and reactive nitrogen species (RNS), fibroblast activity was evaluated in a short time. In skin fibroblast culture, treatment with inhibitors of ROS and RNS synthesis abolished the increase in carbonyl protein content and lipid peroxide accumulation induced by epinephrine. In conclusion, chronic psychological stress may be an important extrinsic factor, which contributes to skin aging in mice.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that people in industrialised countries have a 1% chance of suffering from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 22% of ulcers). Treatment of arterial leg ulcers is directed towards correcting the poor arterial blood supply, for example by correcting arterial blockages (either surgically or pharmaceutically). If the blood supply has been restored, these arterial ulcers can heal following principles of good wound care. Dressings and topical agents make up a part of good wound care for arterial ulcers but there are many products available and it is unclear what impact these have on ulcer healing. This is an update of a review first published in 2003.

OBJECTIVES

To determine whether topical agents and wound dressings affect healing in arterial ulcers. To compare healing rates, patient-centred outcomes and costs between wound dressings and topical agents.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched November 2014) and The Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library) (2014, Issue 10).

SELECTION CRITERIA

Randomised controlled trials (RCTs), or controlled clinical trials (CCTs) evaluating dressings and topical agents in the treatment of arterial leg ulcers were eligible for inclusion. The participants had to have ulcers that were described as arterial, and the time to healing, proportion completely healed, or rate of reduction in ulcer area had to be reported. All wound dressings and topical agents were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The two review authors independently extracted information on the participants' characteristics, the interventions, and outcomes using a standardised data extraction form. Disagreements between the review authors were resolved through discussion.

MAIN RESULTS

One trial met the inclusion criteria, which was a small trial that compared 2% ketanserin ointment in polyethylene glycol (PEG) with vehicle alone (PEG) control, changed twice a day in 40 participants with arterial leg ulcers. The overall quality of the evidence was low with a single small included study which showed inadequate reporting of the results and had too short a follow-up time (eight weeks) to be able to capture sufficient healing events to allow comparisons to be made. In addition, the study was of low methodological quality. The majority of the 'risk of bias' domains received an 'unclear' risk rating as very little information was provided in the text on the methods of the study. The trial demonstrated increased wound healing in the ketanserin group, compared with the control group, but the trial was too small and had too short a follow-up period (eight weeks) to be able to determine whether there was any difference in healing rates. It should also be noted that ketanserin is not licensed in all countries for use in humans.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers.

Cutaneous wound healing of chronically stressed mice is improved through catecholamines blockade

Stress impairs cutaneous wound healing; however, it is unclear how beta-adrenoceptors participates in alterations induced by stress on skin wound repair. Therefore, the aim of this study was to investigate the effects of propranolol, a non-selective beta-blocker, administration on cutaneous wound healing of chronically stressed mice. Male mice were spun at 115 rpm for 15 min every hour from three days before wounding until euthanasia. Control animals were not submitted to stress. Stressed and control animals were treated with propranolol dissolved in water; controls received only water. Propranolol administration began one day before wounding and was continued daily until euthanasia. A full-thickness excisional lesion was performed. Seven and fourteen days later, animals were killed, and lesions were formalin-fixed and paraffin-embedded. Sections were stained with hematoxylin-eosin and immunostained against F4/80 to quantify macrophages, alpha-smooth muscle actin to quantify the myofibroblast density and proliferating cell nuclear antigen to quantify the cell proliferation. Furthermore, matrix metalloproteinases (MMP)-2 and MMP-9 activity, nitrite and hydroxyproline levels and tumor necrosis factor-alpha (TNF-alpha) expression were measured in wound. Stress and control + propranolol groups presented a delay in wound contraction, re-epithelialization, F4/80-positive macrophages, neutrophils and mast cells infiltration, cellular proliferation, angiogenesis, myofibroblastic differentiation, MMP-2 and MMP-9 activation and TNF-alpha expression, whereas an increase in the nitrite levels. Stress + propranolol group presented results similar to control group. In conclusion, stress impairs cutaneous wound healing in mice through beta1- adrenoceptors and beta2-adrenoceptors activation.

Rotational stress-induced increase in epinephrine levels delays cutaneous wound healing in mice

Stress impairs wound healing of cutaneous lesions; however, the mechanism is still unclear. The aim of this study was to evaluate the effects of rotational stress on cutaneous wound healing in mice and propose a mechanism. Male mice were spun at 45 rpm for 15 min every hour beginning 3 days before wounding until euthanasia. Control animals were not subjected to stress. To confirm that catecholamines participate in stress-induced delay of wound healing, mice were treated daily with propranolol. An excisional lesion was created and measured. Seven and 14 days later, animals were killed and lesions collected. Sections were stained with hematoxylin-eosin and immunostained for alpha-smooth muscle actin and proliferating cell nuclear antigen. Matrix metalloproteinase (MMP)-2 and -9 activity, nitrite levels, and tumor necrosis factor-alpha (TNF-alpha) expression were measured in the wounds. In addition, murine skin fibroblast cultures were treated with high levels of epinephrine and fibroblast activity was evaluated. Stressed mice exhibited reduced locomotor activity and increased normetanephrine plasma levels. Rotational stress was associated with decreased wound contraction, reduced re-epithelialization, reduced MMP-2 and MMP-9 activation, but with strongly increased nitrite levels. Furthermore, inflammatory cell infiltration, TNF-alpha expression, myofibroblastic differentiation, and angiogenesis were all delayed in the stress group. Propranolol administration reversed the deleterious effects of stress on wound contraction and re-epithelialization. High epinephrine concentrations increased murine skin fibroblast proliferation and nitric oxide synthesis, and strongly inhibited skin fibroblast migration and both pro- and active MMP-2. In conclusion, rotational stress impairs cutaneous wound healing due to epinephrine increased levels.

beta-1 and beta-2, but not alpha-1 and alpha-2, adrenoceptor blockade delays rat cutaneous wound healing

The sympathetic nervous system plays an important role in wound healing, but its mechanism of action is poorly understood. The aim of this study was to investigate the effects of beta- and alpha-adrenoceptor blockade on cutaneous wound healing. Male rats were treated with propranolol (beta1- and beta2-antagonist), atenolol (beta1-antagonist), or phentolamine (alpha1- and alpha2-antagonist) dissolved in drinking water. A full-thickness excisional lesion was created and the wound area was measured. Fourteen days after wounding, lesions and adjacent skin were removed, formalin-fixed, and paraffin-embedded. Sections were stained with hematoxylin-eosin and toluidine blue, and immunostained for alpha-smooth muscle actin and proliferating cell nuclear antigen. Wound contraction was delayed in propranolol- and atenolol-treated animals but not in phentolamine-treated animals. Reepithelialization was decreased only in propranolol-treated animals. beta1- and beta2-adrenoceptor blockade delayed leukocyte migration, epidermal and connective tissue cell proliferation, myofibroblastic differentiation, and mast cell migration. The volume density of blood vessels was increased in the propranolol- and atenolol-treated animals compared with controls. The levels of matrix metalloproteases (MMP-2 and MMP-9) decreased in the propranolol- and atenolol-treated animals. alpha1- and alpha2-adrenoceptor blockade only affected leukocyte migration, epithelial and connective tissue cell proliferation, and pro-MMP-9 levels. In conclusion, beta-1 and beta-2, but not alpha-1 and alpha-2, adrenoceptor blockade delays cutaneous wound healing.

Hyperglycaemic conditions decrease cultured keratinocyte mobility: implications for impaired wound healing in patients with diabetes

BACKGROUND

Elevated blood glucose in patients with diabetes mellitus (DM) leads to complications including poor wound healing. Proper keratinocyte migration and proliferation are the crucial steps during re-epithelialization. We hypothesize that the impaired wound healing in patients with DM is due to the disruption of proper re-epithelialization.

OBJECTIVES

We aimed to explore the effects of high glucose on keratinocytes in terms of cell migration and proliferation.

METHODS

Keratinocytes were cultivated in normal and high glucose conditions. Their viability was evaluated by MTS assay. Transwell migration and in vitro scratch assays were used to evaluate their mobility. The mRNA expressions and activities of matrix metalloproteinase (MMP)-2 and MMP-9 were determined. The mRNA of their respective physiological inhibitors, tissue inhibitor of MMP (TIMP)-1 and TIMP-2, was also evaluated. Immunofluorescent staining and Western blotting were used to examine the expression of phosphorylated focal adhesion kinase (pp125(FAK)). The impacts of high glucose on keratinocyte proliferation were assessed by 5-bromo-2'-deoxyuridine incorporation assay.

RESULTS

High glucose treatment did not affect keratinocyte viability up to 3 days. In contrast, the mobility of keratinocytes, the activities and gene expressions of MMP-2 and MMP-9, the expression of pp125(FAK), and the cell proliferation after 5 days were significantly downregulated after hyperglycaemic treatments while the mRNA expression of TIMP-1 increased.

CONCLUSIONS

Under hyperglycaemic conditions, keratinocytes demonstrate reduced migration and decreased proliferation capacities. These impairments of keratinocyte functions are likely to result in inadequate re-epithelialization. These defective physiological events provide a reasonable explanation for the poor wound healing commonly observed in patients with DM.