Postural vasoregulation and mediators of reperfusion injury in venous ulceration

Cytokines and Venous Leg Ulcer Healing-A Systematic Review

Venous leg ulcers (VLUs) are the most common type of leg ulcers with a significant socioeconomic burden due to slow healing. Cytokines may be involved in the pathogenesis of VLUs. In this systematic review, our objective was to investigate the association between cytokine levels, including growth factors, with the healing of VLUs. PubMed, Embase, Web of Science and Cochrane Library were searched from their inception to August 2021. We retrieved 28 articles investigating 38 different cytokines in 790 patients. Cytokines were most commonly investigated in wound fluid and less frequently in biopsies and serum. The studies were judged as having a moderate to high risk of bias, and the results were often inconsistent and sometimes conflicting. A meta-analysis was not performed due to clinical and methodological heterogeneities. We found weak evidence for elevated IL-1α, IL-6, IL-8, TNF-α and VEGF levels in non-healing VLUs, an elevation that declined with healing. TGF-β1 levels tended to increase with VLU healing. Other cytokines warranting further investigations include EGF, FGF-2, GM-CSF, IL-1β, IL-1Ra and PDGF-AA/PDGF-BB. We conclude that non-healing VLUs may be associated with an elevation of a palette of pro-inflammatory cytokines, possibly reflecting activated innate immunity in these wounds. There is a paucity of reliable longitudinal studies monitoring the dynamic changes in cytokine levels during wound healing.

Why Venous Leg Ulcers Have Difficulty Healing: Overview on Pathophysiology, Clinical Consequences, and Treatment

Venous leg ulcers (VLUs) are one of the most common ulcers of the lower extremity. VLU affects many individuals worldwide, could pose a significant socioeconomic burden to the healthcare system, and has major psychological and physical impacts on the affected individual. VLU often occurs in association with post-thrombotic syndrome, advanced chronic venous disease, varicose veins, and venous hypertension. Several demographic, genetic, and environmental factors could trigger chronic venous disease with venous dilation, incompetent valves, venous reflux, and venous hypertension. Endothelial cell injury and changes in the glycocalyx, venous shear-stress, and adhesion molecules could be initiating events in VLU. Increased endothelial cell permeability and leukocyte infiltration, and increases in inflammatory cytokines, matrix metalloproteinases (MMPs), reactive oxygen and nitrogen species, iron deposition, and tissue metabolites also contribute to the pathogenesis of VLU. Treatment of VLU includes compression therapy and endovenous ablation to occlude the axial reflux. Other interventional approaches such as subfascial endoscopic perforator surgery and iliac venous stent have shown mixed results. With good wound care and compression therapy, VLU usually heals within 6 months. VLU healing involves orchestrated processes including hemostasis, inflammation, proliferation, and remodeling and the contribution of different cells including leukocytes, platelets, fibroblasts, vascular smooth muscle cells, endothelial cells, and keratinocytes as well as the release of various biomolecules including transforming growth factor-β, cytokines, chemokines, MMPs, tissue inhibitors of MMPs (TIMPs), elastase, urokinase plasminogen activator, fibrin, collagen, and albumin. Alterations in any of these physiological wound closure processes could delay VLU healing. Also, these histological and soluble biomarkers can be used for VLU diagnosis and assessment of its progression, responsiveness to healing, and prognosis. If not treated adequately, VLU could progress to non-healed or granulating VLU, causing physical immobility, reduced quality of life, cellulitis, severe infections, osteomyelitis, and neoplastic transformation. Recalcitrant VLU shows prolonged healing time with advanced age, obesity, nutritional deficiencies, colder temperature, preexisting venous disease, deep venous thrombosis, and larger wound area. VLU also has a high, 50-70% recurrence rate, likely due to noncompliance with compression therapy, failure of surgical procedures, incorrect ulcer diagnosis, progression of venous disease, and poorly understood pathophysiology. Understanding the molecular pathways underlying VLU has led to new lines of therapy with significant promise including biologics such as bilayer living skin construct, fibroblast derivatives, and extracellular matrices and non-biologic products such as poly-N-acetyl glucosamine, human placental membranes amnion/chorion allografts, ACT1 peptide inhibitor of connexin 43, sulodexide, growth factors, silver dressings, MMP inhibitors, and modulators of reactive oxygen and nitrogen species, the immune response and tissue metabolites. Preventive measures including compression therapy and venotonics could also reduce the risk of progression to chronic venous insufficiency and VLU in susceptible individuals.

Priming with a combination of proangiogenic growth factors improves wound healing in normoglycemic mice

Growth factors and/or angiogenic factors are supposed to improve wound healing. The aim of our study was to evaluate the effects of subcutaneous pretreatment with combinatory proangiogenic factors on wound closure, mechanical properties, vessel density and morphology. Twenty-eight Balb/c mice were divided equally into two groups. A mixture of VEGF (35.0 µg), bFGF (2.5 µg) and PDGF (3.5 µg) was administered subcutaneously 3, 5 and 7 days to 14 mice before full thickness skin punch biopsy wounding, whereas 14 control animals received three injections of 0.2 ml saline solution. Wound sizes were assessed daily and the repaired tissues were harvested 7 days after complete wound closure. Complete closure (≥ 95% healing of initial wound area) was reached in all proangiogenic pretreated animals on day 10, whereas controls needed 13 days for complete closure. Tensile strengths were nearly twofold higher compared to the controls (p ≤ 0.01). The punch biopsy material revealed 4.2-fold higher vessel densities in the proangiogenic pretreated group. On day 17, the vessel densities in the proangiogenic pretreated wounds were also 3.2-fold higher compared to the untreated controls. No significant differences were seen in the collagen ratio. Pretreatment with proangiogenic factors revealed several significant effects on wound healing: faster time to closure, a higher vessel density and a better functional outcome. These results suggest a beneficial effect of pretreatment with combinatory growth factors in mouse skin wounds without impaired wound healing. This might be exploited in further investigations in diabetic healing as a therapeutic approach for elective surgery.

Short saphenous vein incompetence and chronic lower extremity venous disease

OBJECTIVE

We performed this prospective study on patients with signs and symptoms of chronic venous disease to emphasize short saphenous vein (SSV) insufficiency, which is not routinely evaluated with Doppler ultrasonography in every center.

METHODS

One hundred seventy-eight patients with signs and symptoms of chronic venous disease were included in the study. We used the CEAP (clinical, etiologic, anatomic, and pathophysiologic data) classification in evaluation of the limbs with isolated and nonisolated SSV incompetence. Patients were classified according to age, occupation, body mass index, and associated chronic illness. A chi(2) test and a t test were used in the statistical analysis.

RESULTS

Reflux was observed in 190 (53%) of 356 limbs. In 11 limbs, isolated SSV reflux was observed. These 11 limbs were classified as CEAP grade 2 (3 limbs), CEAP grade 3 (3 limbs), and CEAP grade 4 (5 limbs). Short saphenous vein reflux was observed in 21 (5.9%) of 356 limbs. Mean SSV diameters were 3.89 mm (range, 1-11 mm) on the right and 4.03 mm (1.3-10 mm) on the left.

CONCLUSIONS

No statistical significance was found between age, sex, body mass index, occupation, and associated chronic disease and deep or superficial venous system incompetence. A statistically significant difference was found between the SSV diameter of the limbs and associated venous incompetence.

Venous hypertension induces increased platelet reactivity and accumulation in patients with chronic venous insufficiency

The objective of this study was to determine whether there are changes in platelet activation and rheology in patients with chronic venous insufficiency (CVI) and what their impact is on this disease. Anticoagulated peripheral venous blood collected from 21 patients with CVI and 13 normal control subjects in different bodily positions was incubated either with 0.5 mumol/L adenosine diphosphate (ADP) or without agonist and analyzed by whole blood flow cytometry. Soluble P-selectin was analyzed in obtained sera by enzyme-linked immunosorbent assay. Platelet count was determined by a whole blood analyzer. Circulating platelets were more reactive to stimulation with 0.5 mumol/L ADP in patients with CVI compared with control subjects. There was no statistically significant change in platelet activation without ADP and the level of soluble P-selectin as a function of posture. Under simulated venous hypertension, platelet accumulation was observed in patients with CVI. Patients with CVI had increased platelet reactivity and accumulation during orthostasis, suggesting this might be a contributory factor to CVI pathogenesis.

Chronic wound pathogenesis and current treatment strategies: a unifying hypothesis

Most chronic wounds can be classified into three major types: pressure ulcers, venous ulcers, and diabetic ulcers. The authors propose a unifying hypothesis of chronic wound pathogenesis based on four main causative factors: local tissue hypoxia, bacterial colonization of the wound, repetitive ischemia-reperfusion injury, and an altered cellular and systemic stress response in the aged patient. Traditional strategies for the treatment of chronic wounds have shown limited success. The authors explore potential treatment regimens specifically aimed at each individual determinant of chronic wound pathogenesis. Furthermore, they explore a combined therapeutic approach that collectively targets all the components of chronic wound pathology. These innovative ideas and therapies could be of substantial interest for clinicians and researchers, while further offering significant benefit to patients with chronic wounds.

Laser Doppler imaging in the investigation of lower limb wounds

Good blood supply is a primary determinant for the healing of acute and chronic wounds alike. Chronic wounds commonly occur in the lower extremity in man. Scientists are forever looking for objective techniques with which tissue perfusion may be measured with accuracy. Laser Doppler imaging is a very useful technique for measuring microvascular perfusion in wounds because it involves no contact and produces a color image representing flow distribution over an area of tissue. In this article, the authors discuss its application to the assessment of lower limb wounds, and they review published studies in which it has been used to investigate a range of wound types. This review examines the study of healing mechanisms, treatment effects, risk prediction, healing potential, and underlying pathology. It also considers areas in which laser Doppler imaging is still to be exploited fully.

Venous disease is associated with an impaired range of ankle movement

OBJECTIVES

to investigate the relationship between clinical severity of venous disease, calf muscle pump dysfunction and range of ankle movement (ROAM).

MATERIALS AND METHODS

ROAM was assessed by goniometry in the supine, nonweightbearing position. Calf muscle pump function was assessed by ambulatory venous pressure (AVP), calculating the pressure relief index (PRI). Venous disease was classified according to the CEAP classification (International Consensus Committee reporting standards on venous disease). Forty seven limbs in 38 adults were recruited and matched for age: 11 normal controls CEAP(0), 12 varicose veins CEAP(2), 12 chronic venous insufficiency CEAP(4,5) and 12 active ulceration CEAP(6).

RESULTS

mean (S.E.M.) age was 60.7 (1.3) years. Mean (S.E.M.) PRI was 1959.6 (313.7) in CEAP(0), 905.3 (139.3) in CEAP(2), 596.5 (148.5) in CEAP(4,5) and 170.6 (69.0) in CEAP(6) (p < 0.001, ANOVA). Mean (S.E.M.) ROAM was 61.3 (2.0) degrees in CEAP(0), but significantly reduced to 49.7 (2.0) in CEAP(2), 42.1 (2.6) in CEAP(4,5) and 40.9 (2.7) in CEAP(6) (p < 0.004, ANOVA post hoc Tukey). PRI correlated with ROAM (p < 0.001, Pearson correlation coefficientr = 0.52).

CONCLUSIONS

limbs with venous hypertension have a reduced range of ankle movement related to the clinical severity of venous disease.

Evidence of oxidative stress in chronic venous ulcers

Reactive oxygen species have been implicated in the impaired healing of chronic leg ulcers but little direct evidence is available. We have observed a significant (p < 0.01) elevation of the allantoin : uric acid percentage ratio, a marker of oxidative stress, in wound fluid from chronic leg ulcers (median 17, range 8-860) compared to both paired plasma (median 2, range 1-8) and acute surgical wound fluid (median 4, range 3-7). However, the allantoin : uric acid percentage ratio did not differ significantly between chronic wounds that healed and those that failed to heal. Neutrophil elastase was elevated 30- to 1300-fold in chronic wound fluid compared to plasma and there was a correlation (r(2) = 0.742) between wound fluid elastase and the allantoin : uric acid percentage ratio. Total antioxidant capacity of wound fluid, as measured with a chemiluminescence assay, did not show a correlation (r(2) = 0.03) with the observed oxidative stress. These observations suggest that conditions of localized oxidative stress, possibly related to neutrophil-associated production of reactive oxygen species, are present in chronic leg ulcers. It is possible that future therapeutic strategies aimed at reducing oxidative stress, in addition to good standard care, could improve healing rates of chronic wounds.

Inflammation. 2: Its role in the healing of chronic wounds

Why do some wounds fail to heal in the expected time? Part two of this article on inflammation discusses the possible causes, which include recurrence of trauma, bacterial and other contamination and perhaps, above all, the ageing process.

Microcirculation in chronic venous insufficiency

In this review, the anatomy and physiology of the venous system and its pathophysiology are described. Theories regarding the possible causes of disturbances in venous microangiopathy are summarized. The theories concern the deoxygenation of red blood cells, arteriovenous shunts, fibrin cuffs, and the trapping of growth factors and/or white blood cells. Furthermore, microlymphatic, neurologic and hemorheologic disturbances in venous disease are outlined. Findings in venous microangiopathy obtained from histology, capillary microscopy, microlymphography, laser Doppler fluxmetry and transcutaneous oxygen partial pressure are detailed. Finally, the recently discovered pattern of perfusion in microcirculation within and around venous ulcers is discussed.

New approaches to the treatment of venous leg ulcers

Increased understanding of the pathology of leg ulcers has made the differences in the pathologies of leg ulcers between patients more apparent. This article examines some areas of research that are advancing our understanding of the pathology of venous leg ulcers. The impact that this information is having on the development of new therapies and the implications for nursing practice are discussed.