Matrix metalloproteinases -8 and -9 and tissue inhibitor of metalloproteinase-1 in burn patients. A prospective observational study

Tissue Inhibitors of Metalloproteinase 1 (TIMP-1) and 3 (TIMP-3) as New Markers of Acute Kidney Injury After Massive Burns

BACKGROUND Acute kidney injury (AKI) is a common and serious complication after massive burn injury. One of the postulated etiologies is destruction of the extracellular matrix of nephrons, caused by a local imbalance between matrix metalloproteinases (MMPs) and specific inhibitors. The aim of this study was to analyze the dynamics of tissue inhibitors of metalloproteinases (TIMPs) during the first 5 days after massive thermal injury and the relationship with the risk of AKI. MATERIAL AND METHODS Thirty-three adults (22 men, 11 women) with severe burns were enrolled in the study. The values of TIMPs 1 to 4 were measured in blood serum and urine using the multiplex Luminex system. The associations between TIMPs and the risk of AKI were analyzed by using the generalized linear mixed models for repeated measurements. RESULTS Significant changes in serum and urine activities of TIMPs were confirmed, especially during the first 2 days after burn injury. Almost half of patients presented renal problems during the study. Significant differences between values of TIMPs in AKI and non-AKI status were also observed. However, a significant relationship between concentration of TIMPs and risk of AKI was confirmed only for urine TIMP-1 and serum TIMP-3. CONCLUSIONS The evaluation of TIMPs in the early stage after burn injury has potential benefits. The important roles of urine TIMP-1 and serum TIMP-3, as novel markers of the risk of AKI development, were confirmed. Other parameters require further analysis.

The Complexity of the Post-Burn Immune Response: An Overview of the Associated Local and Systemic Complications

Burn injury induces a complex inflammatory response, both locally and systemically, and is not yet completely unravelled and understood. In order to enable the development of accurate treatment options, it is of paramount importance to fully understand post-burn immunology. Research in the last decades describes insights into the prolonged and excessive inflammatory response that could exist after both severe and milder burn trauma and that this response differs from that of none-burn acute trauma. Persistent activity of complement, acute phase proteins and pro- and anti-inflammatory mediators, changes in lymphocyte activity, activation of the stress response and infiltration of immune cells have all been related to post-burn local and systemic pathology. This "narrative" review explores the current state of knowledge, focusing on both the local and systemic immunology post-burn, and further questions how it is linked to the clinical outcome. Moreover, it illustrates the complexity of post-burn immunology and the existing gaps in knowledge on underlying mechanisms of burn pathology.

Clinical significance of serum matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in the first phase of burn trauma evolution

No prospective study has specifically examined the serum levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the early shock phase of burn-injured patients. Thus, we aimed to detect early changes, activity dynamics, and the predictive value of MMP-9, TIMP-1, and the MMP-9/TIMP-1 ratio to better understand the early repair mechanisms for the development of future therapies for patients with thermal burns. Twenty-five patients with a total body surface area (TBSA) affected by burn <25%, and 30 healthy subjects were enrolled in the study. Serum levels of MMP-9 and TIMP-1 were determined by the ELISA method. Our results showed that MMP-9 concentrations increased immediately after injury and remained on a plateau. In contrast, TIMP-1 showed an upward trend throughout the 7-day study period, and the time course of the MMP-9/TIMP-1 ratio followed the inverse dynamics of TIMP-1. Analysis of the areas under the receiver operating characteristic (ROC) curves (AUC) showed that patients with burn wounds tended to have a MMP-9 value higher than 421.5 ng/ml (AUC=0.979), TIMP-1 value higher than 231.6 ng/ml (AUC=0.908), and MMP-9/TIMP-1 ratio higher than 2.31 (AUC=0.959) (P<0.001). Our findings suggest that although the variations in the two biomarkers were different regarding the time of the initial insult, their ratio is a specific and sensitive indicator of burn evolutivity in patients with a TBSA affected by a burn <25%.

Role and dynamics of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in burn patients

Burn injuries can trigger tissue changes that can explain the variation in the level of different biochemical markers that can be recorded both locally or systemically. Some events observed in burn wounds such as vascular hyperpermeability have been associated with the release of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) after trauma. Because it is unknown whether the serum levels of MMP-9 and TIMP-1 are a consequence of these destructions or a local response to thermal damage, we decided to follow their dynamics. Twenty-five patients (mean age 49.40±17.55 years) with a total body surface area (TBSA) affected by a thermal burn of <25% and 30 healthy subjects (mean age 49.70±8.04 years) were enrolled in the present study. Enzyme immunoassays were used to measure the serum levels of MMP-9 and TIMP-1. Our results showed that MMP-9 was increased 6.25-fold immediately after injury compared to the controls and remained on a plateau throughout the 7-day monitoring period. TIMP-1 showed an upward trend with an increase of 49.52% on the seventh day after triggering insult. The time-course of the MMP-9/TIMP-1 ratio followed the inverse dynamics of TIMP-1 starting from a ratio value measured at admission 3.82-fold higher than the one observed in the healthy volunteers and a highly statistically significant correlation between the values measured at different time-points during the monitoring period (P<0.001). The results of this retrospective study indicate that the MMP-9/TIMP-1 ratio may provide information on local changes over time, starting from the triggering insult, and may be considered as a predictive biomarker of burn evolutivity.

The role of matrix metalloproteinase-9 and its inhibitor TIMP-1 in burn injury: a systematic review

Matrix metalloproteinase-9 (MMP-9) and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), are key mediators of acute inflammation and regulators of the wound healing process. The aim of this systematic review was to determine the local and systemic involvement of the MMP-9/TIMP-1 system following burn injury. Two databases (Scopus and MEDLINE) were searched for all studies reporting MMP-9 and/or TIMP-1 after burn injury. Based on our eligibility criteria, we reviewed 24 studies involving 508 burns patients in 11 clinical studies and 367 animals in 13 preclinical studies. Local, systemic, and peripheral gene expression, protein levels and activity of MMP-9 and TIMP-1 were assessed. Increased MMP-9 was reported at the site of injury early after burn trauma in all studies, and remained elevated in non-healing wounds. Increased TIMP-1 expression in burn wounds occurred later than MMP-9, and was persistent in hypertrophic burn scars. Similar to local expression, systemic MMP-9 and TIMP-1 concentrations were significantly elevated after burn injury in response to upregulation of proinflammatory cytokines. While no association was found between systemic MMP-9 concentration and extent of injury or outcome, serum or plasma TIMP-1 showed good correlation with survival and burn severity. This review also found evidence of the MMP-9/TIMP-1 system contributing to secondary tissue damage distant from the burn site, including burn-associated musculoskeletal damage and acute lung injury. In addition, increased MMP-9 synthesis and activity in the brain after peripheral burn may lead to blood-brain barrier dysfunction and cerebral edema, a significant contributor to mortality. This systematic review provides an overview of the available evidence of the role of MMP-9 and TIMP-1 in burn injury pathophysiology and finds that TIMP-1 may be a promising biomarker in outcome prognostication of burns patients. Large-scale studies of both pediatric and adult burns patients with increased female representation and repeated sampling are recommended to validate the reliability of TIMP-1 as a prognostic marker following burn injury.

Activated matrix metalloproteinase 8 in serum predicts severity of acute pancreatitis

OBJECTIVES

Severe acute pancreatitis (SAP) has high morbidity and mortality but there are no widely accepted predictive biomarkers in clinical use. Matrix metalloproteinases (MMPs) are active in tissue destruction and inflammatory responses. We studied whether serum levels of activated MMP-8 (aMMP-8), MMP-9 and their regulators tissue inhibitor of matrix metalloproteinases (TIMP)-1, myeloperoxidase (MPO) and human neutrophil elastase (HNE) could predict the development of SAP.

METHODS

The study comprised 214 AP patients (revised Atlanta classification: 142 mild, MAP; 54 moderately severe, MSAP; 18 SAP) referred to Helsinki University Hospital. A venous blood sample was taken within 72 h from the onset of symptoms. Serum levels of aMMP-8 were determined using immunofluorometric assay, and those of MMP-9, TIMP-1, MPO and HNE using enzyme-linked immunosorbent assay. AP groups were compared using Jonckheere-Terpstra test and predictive value for SAP was analyzed using receiver operating characteristics (ROC) analysis.

RESULTS

Serum aMMP-8 levels were higher in SAP (median 657 ng/ml, interquartile range 542-738 ng/ml) compared to MSAP (358 ng/ml, 175-564 ng/ml; p < 0.001) and MAP (231 ng/ml, 128-507 ng/ml; p < 0.001). Similar trend was seen with TIMP-1 and MPO. In ROC analysis aMMP-8, MPO and TIMP-1 emerged as potential markers for the development of SAP (areas under ROC curves 0.83, 0.71 and 0.69, respectively).

CONCLUSIONS

Serum aMMP-8 measured early in the course of AP (within 72 h of symptom onset) predicted the development of SAP.

MMP-9 Concentration in Peritoneal Fluid Is a Valuable Biomarker Associated with Endotoxemia in Equine Colic

The purpose of the study was to compare the results of sepsis scoring (clinical examination and clinical pathology) to the concentrations of matrix-metalloproteinases (MMPs) -2, -8, and -9; tissue-inhibitor of metalloproteinases (TIMPs) -1 and -2; and inflammatory chemokines interleukin (IL) 1β and tumor-necrosis-factor-alpha (TNF-α) in plasma and peritoneal fluid of equine colic patients. A modified sepsis scoring including general condition, heart and respiratory rate, rectal temperature, mucous membranes, white blood cell count (WBC), and ionized calcium was applied in 47 horses presented with clinical signs of colic. Using this scoring system, horses were classified as negative (n = 32, ≤6/19 points), questionable (n = 9, 7-9/19 points), or positive (n = 6, ≥10/19 points) for sepsis. MMPs, TIMPs, IL-1β, and TNF-α concentrations were evaluated in plasma and peritoneal fluid using species-specific sandwich ELISA kits. In a linear discriminant analysis, all parameters of sepsis scoring apart from calcium separated well between sepsis severity groups (P < 0.05). MMP-9 was the only biomarker of high diagnostic value, while all others remained insignificant. A significant influence of overall sepsis scoring on MMP-9 was found for peritoneal fluid (P = 0.005) with a regression coefficient of 0.092, while no association was found for plasma (P = 0.085). Using a MMP-9 concentration of >113 ng/ml in the peritoneal fluid was found to be the ideal cutoff to identify positive sepsis scoring (≥10/19 points; sensitivity of 83.3% and specificity of 82.9%). In conclusion, MMP-9 was found to be a biomarker of high diagnostic value for sepsis and endotoxemia in equine colic. The evaluation of peritoneal fluid seems preferable in comparison to plasma. As abdominocentesis is commonly performed in the diagnostic work-up of equine colic, a pen-side assay would be useful and easy-to-perform diagnostic support in the decision for therapeutic intervention.

Protease levels are significantly altered in pediatric burn wounds

Burn wounds contain high levels of protease activity due to the need to remodel the damaged extracellular matrix proteins. While necessary, excessive protease activity can lead to improper wound healing and is associated with increased contraction and fibrosis. No studies to date have investigated the expression changes of all the collagenases and elastases in burn wounds. The present study compares gene expression changes and changes in collagenase and elastase activity between burn wound eschar and normal skin in a pediatric population. Deidentified pediatric tissues were used for these experiments. Burn wound tissue was excised as part of normal standard care within a week from injury; normal skin was removed during elective plastic surgery procedures. RNA-sequencing was performed and significant results were confirmed with qRT-PCR. Activity assays showed a significant increase in both collagenase and elastase activity in the burn wound tissue compared to the normal skin. Western blotting and substrate zymography of tissue homogenates evaluated the results at the protein levels. Four elastases and three collagenases were determined to be significantly upregulated in the wound tissues by both RNA-sequencing and qRT-PCR. Cathepsin V was the only protease that was significantly downregulated. All but one metalloproteinase studied was significantly upregulated. None of the serine proteases were significantly altered in the wound tissues. In conclusion, matrix metalloproteinases appear to be the most highly elevated proteases after a pediatric burn wound injury, at least within the first 3-7 days. The data warrant further investigation into the effects of MMPs on burn wound healing.

Stimuli-Responsive Delivery of Growth Factors for Tissue Engineering

Growth factors (GFs) play a crucial role in directing stem cell behavior and transmitting information between different cell populations for tissue regeneration. However, their utility as therapeutics is limited by their short half-life within the physiological microenvironment and significant side effects caused by off-target effects or improper dosage. "Smart" materials that can not only sustain therapeutic delivery over a treatment period but also facilitate on-demand release upon activation are attracting significant interest in the field of GF delivery for tissue engineering. Three properties are essential in engineering these "smart" materials: 1) the cargo vehicle protects the encapsulated therapeutic; 2) release is targeted to the site of injury; 3) cargo release can be modulated by disease-specific stimuli. The aim of this review is to summarize the current research on stimuli-responsive materials as intelligent vehicles for controlled GF delivery; Five main subfields of tissue engineering are discussed: skin, bone and cartilage, muscle, blood vessel, and nerve. Challenges in achieving such "smart" materials and perspectives on future applications of stimuli-responsive GF delivery for tissue regeneration are also discussed.

Polytrauma in Older Adults Leads to Significantly Increased TIMP-1 Levels in the Early Posttraumatic Period

Background

Patients after polytrauma regularly suffer from posttraumatic immune system destabilization, which closely influences the further clinical development. Increasing age has recently been identified as an isolated risk factor for an adverse outcome after major trauma. Higher rates and intensity of acute inflammation following severe injury suggest that deregulated inflammation may contribute to these higher rates of posttraumatic morbidity and mortality in older adults. MMP-9 and TIMP-1 have been found to play a major role in posttraumatic immune disorder in a previous genome-wide mRNA analysis.

Objective

The aim of this study was to evaluate the differences in serum protein dynamics in older and younger polytraumatized adults.

Methods

Blood samples were drawn immediately within 90 minutes after trauma and subsequently after 6, 12, 24, 48, and 72 h. Serum levels of TIMP-1 and MMP-9 were quantified using ELISA. Age groups were divided according to a cutoff of 60 years.

Results

60 polytrauma patients (ISS > 16) were included (<60 years, n = 49; ≥60 years, n = 49; ≥60 years, n = 11). Serum TIMP-1 and MMP-9 levels showed a highly significant serum dynamic in young and old polytrauma patients (p < 0.001). Patients ≥ 60 years showed significantly higher overall TIMP-1 levels (p < 0.001). Patients ≥ 60 years showed significantly higher overall TIMP-1 levels (p = 0.008). TIMP-1 levels showed a significant maximum after 72 h in the older study population. MMP-9 levels were nonsignificantly higher during the whole observational period in older polytrauma patients when compared to younger patients.

Conclusion

The posttraumatic immune response is characterized by significantly higher TIMP-1 levels in older polytrauma patients. This significant association between TIMP-1 levels and patients' age indicates a more extensive immune dysregulation following major trauma in older adults.

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.

Updating the role of matrix metalloproteinases in mineralized tissue and related diseases

Bone development and healing processes involve a complex cascade of biological events requiring well-orchestrated synergism with bone cells, growth factors, and other trophic signaling molecules and cellular structures. Beyond health processes, MMPs play several key roles in the installation of heart and blood vessel related diseases and cancer, ranging from accelerating metastatic cells to ectopic vascular mineralization by smooth muscle cells in complementary manner. The tissue inhibitors of MMPs (TIMPs) have an important role in controlling proteolysis. Paired with the post-transcriptional efficiency of specific miRNAs, they modulate MMP performance. If druggable, these molecules are suggested to be a platform for development of "smart" medications and further clinical trials. Thus, considering the pleiotropic effect of MMPs on mammals, the purpose of this review is to update the role of those multifaceted proteases in mineralized tissues in health, such as bone, and pathophysiological disorders, such as ectopic vascular calcification and cancer.

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.

[Influence of massive blood transfusion and traumatic brain injury on TIMP‑1 and MMP‑9 serum levels in polytraumatized patients]

BACKGROUND

The morbidity and mortality of polytrauma patients are substantially influenced by the extent of the posttraumatic inflammatory reaction. Studies have shown that TIMP‑1 and MMP‑9 play a major role in posttraumatic immune disorder in genome-wide mRNA microarray analyses. Furthermore, both showed differential gene expression profiles depending on the clinical parameters massive blood transfusion and traumatic brain injury.

OBJECTIVE

The aim of this study was to evaluate TIMP‑1 and MMP‑9 serum concentrations in polytraumatized patients depending on the clinical parameters massive blood transfusion and traumatic brain injury in the early posttraumatic phase.

MATERIAL AND METHODS

Polytrauma patients (≥18 years) with an "Injury Severity Score" (ISS) ≥ 16 points were enrolled in this prospective study. Serum levels of TIMP‑1 and MMP‑9 were quantified (at 0 h, 6 h, 12 h, 24 h, 48 h and 72 h) using an enzyme-linked immunosorbent assay (ELISA). Groups were divided according to the clinical parameter massive blood transfusion (≥10 red blood cell units [RBC units] in the first 24-hour posttrauma) and traumatic brain injury (CCT postive [cranial computed tomography]).

RESULTS

Following massive blood transfusion (n = 21; 50 ± 15.7 years; ISS 39 ± 12.8 points) patients showed overall significantly increased TIMP‑1 levels (p = 0.003) and significantly higher TIMP‑1 values after 12-72 h. Traumatic brain injury patients (n = 28; 44 ± 19 years; ISS 42 ± 10 points) showed significantly higher MMP‑9 levels (p = 0.049) in the posttraumatic period.

CONCLUSION

Polytraumatized patients who received massive blood transfusions following major trauma showed significantly higher TIMP‑1 levels than patients who did not receive massive transfusions. This seems to be an expression of a massively excessive inflammatory reaction and therefore represents a substantial factor in the pathogenesis of severe posttraumatic immune dysfunction in this collective. Furthermore, the significant increase in MMP‑9 with accompanying traumatic brain injury reflects the pivotal role of matrix metalloproteinases in the pathophysiology of traumatic brain injury.

The time-course of the inflammatory response to major burn injury and its relation to organ failure and outcome

Burn injury causes major inflammatory activation and cytokine release, however, the temporal resolution of the acute and sub-acute inflammatory response has not yet been fully delineated. To this end, we have quantified 20 inflammatory mediators in plasma from 44 adult patients 0-21 days after burn injury and related the time course of these mediators to % total body surface area (TBSA) burned, clinical parameters, organ failure and outcome. Of the cytokines analyzed in these patients, interleukin 6 (IL-6), IL-8, IL-10 and monocyte chemoattractant protein 1 (MCP-1) correlated to the size of the injury at 24-48h after burn injury. In our study, the concentration of IL-10 had prognostic value in patients with burn injury both measured at admission and at 24-48h after injury. However, simple demographic data such as age, % burned TBSA, inhalation injury and their combination, the Baux score and modified Baux score, outperform most of the cytokines, with the exception of IL-8 and MCP-1 levels on admission, in predicting death.

Matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in paediatric burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors

The purpose of this study was the determination of matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in the blood plasma of burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors.

MATERIAL AND METHODS

31 children scalded by hot water who were managed at the Department of Paediatric Surgery between 2014-2015, after primarily presenting with burns in 4-20% TBSA were included into the study (age 9 months up to 14 years, mean age 2,5+1 years). There were 10 girls and 21 boys. Venous blood samples were drawn 2-6h, and 12-16h after the thermal injury, and on the subsequent days 3, 5 and 7. The matrix metalloproteinase-2, collagen type IV and laminin-5 concentrations were assessed using Surface Plasmon Resonance Imaging by the investigators blinded to the other data.

RESULTS

The MMP-2, laminin-5 and collagen type IV concentrations in the blood plasma of patients with burns, were highest 12-16h after thermal injury, the difference was statistically significant. The MMP-2, laminin-5 and collagen type IV concentrations measured 3 days, 5 days and 7 days after the thermal injury, slowly decreased over time, and on the 7th day reached the normal range, when compared with the concentration measured in controls.

CONCLUSION

Current work is the first follow-up study regarding MMP-2 in burns. MMP-2, laminin-5 and collagen type IV levels were elevated early after burn injury in the plasma of studied patients, and were highest 12-16h after the injury. MMP-2, laminin-5 and collagen type IV levels were not proportional to the severity of the burn. We believe in the possibility that the gradual decrease of MMP-2, collagen type IV and laminin-5 concentrations could be connected with the process of healing, but to prove it, more investigation is needed in this area. The SPR imaging biosensor is a good diagnostic tool for determination of MMP-2, laminin-5 and collagen type IV in blood plasma of patients with burns.

Transcription factor 21 (TCF21) promotes proinflammatory interleukin 6 expression and extracellular matrix remodeling in visceral adipose stem cells

The visceral (VIS) and subcutaneous (SQ) fat pads are developmentally distinct white adipose tissue depots and contribute differently to inflammation and insulin resistance associated with obesity. The basic helix-loop-helix transcriptional regulator, transcription factor 21 (TCF21), is a marker gene for white adipose tissues and is abundantly expressed in VIS-derived adipose stem cells (ASCs), but not in SQ-derived ASCs. However, TCF21's role in regulating fat depot-specific gene expression and function is incompletely understood. Here, using siRNA-mediated Tcf21 knockdowns and lentiviral gene transfer of TCF21 in mouse ASCs, we demonstrate that TCF21 is required for the VIS ASC-specific expression of interleukin 6 (IL6), a key cytokine that contributes to the proinflammatory nature of VIS depots. Concurrently, TCF21 promotes MMP-dependent collagen degradation and type IV collagen deposition through the regulation of the extracellular matrix (ECM) modifiers, matrix metalloproteinase (MMP) 2, MMP13, and tissue inhibitor of MMP1 (TIMP1), as well as collagen type IV α1 chain (COL4A1) in VIS ASCs. We also found that although IL6 mediates the expression of Mmp13 and Timp1 in VIS ASCs, the TCF21-dependent expression of Mmp2 and Col4a1 is IL6-independent. These results suggest that TCF21 contributes to the proinflammatory environment in VIS fat depots and to active ECM remodeling of these depots by regulating IL6 expression and MMP-dependent ECM remodeling in a spatiotemporally coordinated manner.

Impairment of tear film and the ocular surface in patients with facial burns

AIM

The aim of this study is to investigate the factors affecting tear film and ocular surface in patients with facial burns.

METHODS

A total of 273 patients with facial burns, treated at Hallym University Hangang Sacred Heart Hospital from November 2012 to July 2015, were included. Tear break-up time (TBUT), Schirmer's tear secretion test, fluorescein staining score (FSS), ocular surface disease index (OSDI), and visual analogue pain score (VAS) were compared according to burned surface area, burn site, burn cause, time since burn injury, or lid abnormality.

RESULTS

Mean age was 48.66±14.46years (range: 18-85). Tear film stability was not different according to burn area, burn site, or burn cause. Facial burn patients with lid abnormalities had shorter TBUT and higher OSDI scores compared to no lid abnormality (p<0.001 and 0.015, independent t-test). There was no difference in TBUT and tear secretion according to area, site, or cause of burn. FSS was different according to the area of burn (p=0.007, ANOVA). OSDI and VAS was higher in the patients with an electrical burn compared to thermal burn (p=0.003 and 0.024, ANOVA).

CONCLUSIONS

Facial burn patients with lid abnormalities had tear film instability and ocular discomforts. Aggressive treatment may be of benefit in facial burn patients with lid involvement. Electrical burn caused more severe pain compared to thermal burn. Attention should be paid to pain control in patients with electrical burns.