Low circulating protein C levels are associated with lower leg ulcers in patients with diabetes

Challenges in the Management of Large Burns

Large burns provoke profound pathophysiological changes. Survival rates of patients with large burns have improved significantly with the advancement of critical care and adaptation of early excision protocols. Nevertheless, care of large burn wounds remains challenging secondary to limited donor sites, prolonged time to wound closure, and immunosuppression. The development of skin substitutes and new grafting techniques decreased time to wound closure. Individually, these methods have limited success, but a combination of them may yield more successful outcomes. Early identification of patients with likely poor prognosis should prompt goals of care discussion and involvement of a palliative care team when possible.

Pro- and Anti-Angiogenic Factors: Their Relevance in Diabetic Foot Syndrome-A Review

Peripheral arterial disease can involve tissue loss in up to 50% of patients with diabetic foot syndrome (DFS). Consequently, revascularization of narrowed or occluded arteries is one of the most common forms of comprehensive treatment. However, technically successful angioplasty does not always result in the healing of ulcers. The pathomechanism of this phenomenon is still not fully understood, but inadequate angiogenesis in tissue repair may play an essential role. Changes in pro- and anti-angiogenic factors among patients with DFS are not always clear and conclusive. In particular, some studies underline the role of decreased concentration of pro-angiogenic factors and higher levels of anti-angiogenic mediators. Nevertheless, there are still controversial issues, including the paradox of impaired wound healing despite high concentrations of some pro-angiogenic factors, dynamics of their expression during the healing process, and their mutual relationships. Exploring this process among diabetic patients may provide new insight into well-known methods of treatment and show their real benefits and chances for improving outcomes.

A Critical Update of the Assessment and Acute Management of Patients with Severe Burns

Significance: Burns are debilitating, life threatening, and difficult to assess and manage. Recent advances in assessment and management have occurred since a comprehensive review of the care of patients with severe burns was last published, which may influence research and clinical practice. Recent Advances: Recent advances have occurred in the understanding of burn pathophysiology, which has led to the identification of potential biomarkers of burn severity, such as protein C. There is new evidence about the potential superiority of natural colloids over crystalloids during fluid resuscitation, and new evidence about components of initial and perioperative management, including an improved understanding of pain following burns. Critical Issues: The limitations of the clinical examination highlight the need for imaging and biomarkers to assist in estimations of burn severity. Fluid resuscitation reduces mortality, although there is conjecture over the ideal method. The subsequent perioperative period is associated with significant morbidity and the evidence for preventing and treating pain, infection, and fluid overload while maximizing wound healing potential is described. Future Directions: Promising developments are ongoing in imaging technology, histopathology, biomarkers, and wound healing adjuncts such as hyperbaric oxygen therapy, topical negative pressure therapy, stem cell treatments, and skin substitutes. The greatest benefit from further research on management of patients with burns would most likely be derived from the elucidation of optimal fluid resuscitation protocols, pain management protocols, and surgical techniques from randomized controlled trials.

Plasma protein C levels are directly associated with better outcomes in patients with severe burns

Protein C circulates in human plasma to regulate inflammation and coagulation. It has shown a crucial role in wound healing in animals, and low plasma levels predict the presence of a wound in diabetic patients. However, no detailed study has measured protein C levels in patients with severe burns over the course of a hospital admission. A severe burn is associated with dysfunction of inflammation and coagulation as well as a significant risk of morbidity and mortality. The current methods of burn assessment have shortcomings in reliability and have limited prognostic value. The discovery of a biomarker that estimates burn severity and predicts clinical events with greater accuracy than current methods may improve management, resource allocation and patient counseling. This is the first study to assess the potential role of protein C as a biomarker of burn severity. We measured the plasma protein C levels of 86 patients immediately following a severe burn, then every three days over the first three weeks of a hospital admission. We also analysed the relationships between burn characteristics, blood test results including plasma protein C levels and clinical events. We used a primary composite outcome of increased support utilisation defined as: a mean intravenous fluid administration volume of five litres or more per day over the first 72 h of admission, a length of stay in the intensive care unit of more than four days, or greater than four surgical procedures during admission. The hypothesis was that low protein C levels would be negatively associated with increased support utilisation. At presentation to hospital after a severe burn, the mean plasma protein C level was 76 ± 20% with a range of 34-130% compared to the normal range of 70-180%. The initial low can be plausibly explained by impaired synthesis, increased degradation and excessive consumption of protein C following a burn. Levels increased gradually over six days then remained at a steady-state until the end of the inpatient study period, day 21. A multivariable regression model (Nagelkerke's R² = 0.83) showed that the plasma protein C level on admission contributed the most to the ability of the model to predict increased support utilisation (OR = 0.825 (95% CI = 0.698-0.977), P = 0.025), followed by burn size (OR = 1.252 (95% CI = 1.025-1.530), P = 0.027), burn depth (partial thickness was used as the reference, full thickness OR = 80.499 (1.569-4129.248), P = 0.029), and neutrophil count on admission (OR = 1.532 (95% CI = 0.950-2.473), P = 0.08). Together, these four variables predicted increased support utilisation with 93.2% accuracy, 83.3% sensitivity and 97.6% specificity. However if protein C values were disregarded, only 49.5% of the variance was explained, with 82% accuracy, 63% sensitivity and 91.5% specificity. Thus, protein C may be a useful biomarker of burn severity and study replication will enable validation of these novel findings.

Activated Protein C in Cutaneous Wound Healing: From Bench to Bedside

Independent of its well-known anticoagulation effects, activated protein C (APC) exhibits pleiotropic cytoprotective properties. These include anti-inflammatory actions, anti-apoptosis, and endothelial and epithelial barrier stabilisation. Such beneficial effects have made APC an attractive target of research in a plethora of physiological and pathophysiological processes. Of note, the past decade or so has seen the emergence of its roles in cutaneous wound healing-a complex process involving inflammation, proliferation and remodelling. This review will highlight APC's functions and mechanisms, and detail its pre-clinical and clinical studies on cutaneous wound healing.

Inflammation in Chronic Wounds

Non-healing chronic wounds present a major biological, psychological, social, and financial burden on both individual patients and the broader health system. Pathologically extensive inflammation plays a major role in the disruption of the normal healing cascade. The causes of chronic wounds (venous, arterial, pressure, and diabetic ulcers) can be examined through a juxtaposition of normal healing and the rogue inflammatory response created by the common components within chronic wounds (ageing, hypoxia, ischaemia-reperfusion injury, and bacterial colonisation). Wound bed care through debridement, dressings, and antibiotics currently form the basic mode of treatment. Despite recent setbacks, pharmaceutical adjuncts form an interesting area of research.

Wounds in patients with HIV

Highly active antiretroviral therapy has dramatically reduced morbidity and mortality among patients who are HIV-positive. A retrospective review of the authors' data separated subjects into cohorts based on HIV status and matched them for age and gender. The authors' data reveal a higher fraction of venous ulcers compared with a lower fraction of pressure ulcers in the seropositive population.

Diabetes increases the risk of deep-vein thrombosis and pulmonary embolism. A population-based cohort study

We evaluated the effects of diabetes on the risks of developing deep-vein thrombosis (DVT) and pulmonary embolism (PE) in a nationwide, population-based cohort study in Taiwan. The patients with newly diagnosed type 2 diabetes mellitus (T2DM) were identified, and DM-free controls were randomly selected from the general population and frequency-matched according to age, sex, and index year by using the records of the Longitudinal Health Insurance Database between 2000 and 2011. Both cohorts were followed up until the end of 2011 to measure the incidence of DVT and PE. We analysed the risks of DVT and PE using Cox proportional-hazards regression models. The overall incidence of VTE was higher in the T2DM patients than in the controls (12.0 vs 7.51 per 10,000 person-years). The T2DM patients exhibited a 1.44-fold adjusted hazard ratio (aHR) of VTE development compared with the controls (95% confidence interval [CI] = 1.27-1.63). The risks of DVT (aHR = 1.43, 95% CI = 1.23-1.65) and PE (aHR = 1.52, 95% CI = 1.22-1.90) were greater in the T2DM than those in the controls. The T2DM patients had a substantially higher risk of DVT (aHR = 5.10, 95% CI = 3.12-8.32) and PE (aHR = 7.50, 95% CI = 3.29-17.1) development than the controls did in adults aged 49 years and younger. In conclusion, the longitudinal nationwide cohort study indicated that T2DM patients carried greater risks of developing VTE than did the general population.

Protein z exerts pro-angiogenic effects and upregulates CXCR4

Objective

Protein Z (PZ) is a vitamin K-dependent coagulation factor without catalytic activity. Evidence points towards PZ as an independent risk factor for the occurrence of human peripheral arterial disease. However, the role of PZ in ischemia-driven angiogenesis and vascular healing processes has not been elucidated so far.

Approach

Angiogenic potency of PZ was assessed in established in vitro assays using endothelial cells. PZ-deficient (PZ^−/−) mice and their wild-type littermates (PZ^+/+) were subjected to hindlimb ischemia. Furthermore, PZ^−/− mice were exposed to PZ expressing adenovirus (AdV-PZ) or control adenovirus (AdV-GFP). In an additional set of animals, PZ^−/− mice were exposed to AdV-PZ and AdV-GFP, each in combination with the CXCR4 antagonist AMD3100.

Results

In vitro, PZ stimulated migratory activity and capillary-like tube formation of endothelial cells comparable to SDF-1. PZ^−/− mice exhibited diminished hypoxia-driven neovascularization and reperfusion in post-ischemic hindlimbs, which was restored by adenoviral gene transfer up to levels seen in PZ^+/+ mice. The stimulatory impact of PZ on endothelial cells in vitro was abolished by siRNA targeting against PZ and PZ was not able to restore reduced migration after knock-down of CXCR4. The increased surface expression of CXCR4 on PZ-stimulated endothelial cells and the abrogated restoration of PZ^−/− mice via AdV-PZ after concomitant treatment with the CXCR4 antagonist AMD3100 supports the idea that PZ mediates angiogenesis via a G-protein coupled pathway and involves the SDF-1/CXCR4 axis. This is underlined by the fact that addition of the G-protein inhibitor PTX to PZ-stimulated endothelial cells abolished the effect of PZ on capillary-like tube formation.

Conclusions

The results of the current study reveal a role of PZ in ischemia-induced angiogenesis, which involves a G-protein coupled pathway and a raised surface expression of CXCR4. Our findings thereby extend the involvement of PZ from the coagulation cascade to a beneficial modulation of vascular homeostasis.

Activated protein C based therapeutic strategies in chronic diseases

Activated protein C (aPC) is a natural anticoagulant and a potent anti-inflammatory and cytoprotective agent. At the expense of increased bleeding risk aPC has been used - with some success - in sepsis. The design of cytoprotective-selective aPC variants circumvents this limitation of increased bleeding, reviving the interest in aPC as a therapeutic agent. Emerging studies suggest that aPC`s beneficial effects are not restricted to acute illness, but likewise relevant in chronic diseases, such as diabetic nephropathy, neurodegeneration or wound healing. Epigenetic regulation of gene expression, reduction of oxidative stress, and regulation of ROS-dependent transcription factors are potential mechanisms of sustained cytoprotective effects of aPC in chronic diseases. Given the available data it seems questionable whether a unifying mechanism of aPC dependent cytoprotection in acute and chronic diseases exists. In addition, the signalling pathways employed by aPC are tissue and cell specific. The mechanistic insights gained from studies exploring aPC`s effects in various diseases may hence lay ground for tissue and disease specific therapeutic approaches. This review outlines recent investigations into the mechanisms and consequences of long-term modulation of aPC-signalling in models of chronic diseases.