Functional analysis of T lymphocytes infiltrating the dermis and epidermis of post-burn hypertrophic scar tissues

OMICS Approaches Evaluating Keloid and Hypertrophic Scars

Abnormal scar formation during wound healing can result in keloid and hypertrophic scars, which is a major global health challenge. Such abnormal scars can cause significant physiological pain and psychological distress and become a financial burden. Due to the biological complexity of scar formation, the pathogenesis of such scars and how to prevent them from forming remains elusive. In this review paper, we delve into the world of "omics" approaches to study abnormal scars and provide examples of genomics, transcriptomics, proteomics, epigenomics, and metabolomics. The benefits of "omics" approaches are that they allow for high-throughput studies and the analysis of 100s to 1000s of genes and proteins with the accumulation of large quantities of data. Currently in the field, there is a lack of "omics" review articles describing pathological scars. In this review, we summarize genome-wide linkage analysis, genome-wide association studies, and microarray data to name a few omics technologies. Such data can provide novel insights into different molecular pathways and identify novel factors which may not be captured through small-scale laboratory techniques.

Evaluation of the Effects of Human Dental Pulp Stem Cells on the Biological Phenotype of Hypertrophic Keloid Fibroblasts

OBJECTIVE

Despite numerous existing treatments for keloids, the responses in the clinic have been disappointing, due to either low efficacy or side effects. Numerous studies dealing with preclinical and clinical trials have been published about effective therapies for fibrotic diseases using mesenchymal stem cells; however, no research has yet been reported to scientifically investigate the effect of human dental pulp stem cells (HDPSCs) on the treatment of keloids. The objective is to provide an experimental basis for the application of stem cells in the treatment of keloids.

METHODS

Human normal fibroblasts (HNFs) and human keloid fibroblasts (HKFs) were cultured alone and in combination with HDPSCs using a transwell cell-contact-independent cell culture system. The effects of HDPSCs on HKFs were tested using a CCK-8 assay, live/dead staining assay, quantitative polymerase chain reaction, Western blot and immunofluorescence microscopy.

RESULTS

HDPSCs did not inhibit the proliferation nor the apoptosis of HKFs and HNFs. HDPSCs did, however, inhibit their migration. Furthermore, HDPSCs significantly decreased the expression of profibrotic genes (CTGF, TGF-β1 and TGF-β2) in HKFs and KNFs (p < 0.05), except for CTGF in HNFs. Moreover, HDPSCs suppressed the extracellular matrix (ECM) synthesis in HKFs, as indicated by the decreased expression of collagen I as well as the low levels of hydroxyproline in the cell culture supernatant (p < 0.05).

CONCLUSIONS

The co-culture of HDPSCs inhibits the migration of HKFs and the expression of pro-fibrotic genes, while promoting the expression of anti-fibrotic genes. HDPSCs' co-culture also inhibits the synthesis of the extracellular matrix by HKFs, whereas it does not affect the proliferation and apoptosis of HKFs. Therefore, it can be concluded that HDPSCs can themselves be used as a tool for restraining/hindering the initiation or progression of fibrotic tissue.

Molecular Changes Underlying Hypertrophic Scarring Following Burns Involve Specific Deregulations at All Wound Healing Stages (Inflammation, Proliferation and Maturation)

Excessive connective tissue accumulation, a hallmark of hypertrophic scaring, results in progressive deterioration of the structure and function of organs. It can also be seen during tumor growth and other fibroproliferative disorders. These processes result from a wide spectrum of cross-talks between mesenchymal, epithelial and inflammatory/immune cells that have not yet been fully understood. In the present review, we aimed to describe the molecular features of fibroblasts and their interactions with immune and epithelial cells and extracellular matrix. We also compared different types of fibroblasts and their roles in skin repair and regeneration following burn injury. In summary, here we briefly review molecular changes underlying hypertrophic scarring following burns throughout all basic wound healing stages, i.e. during inflammation, proliferation and maturation.

T Cells in Fibrosis and Fibrotic Diseases

Fibrosis is the extensive deposition of fibrous connective tissue, and it is characterized by the accumulation of collagen and other extracellular matrix (ECM) components. Fibrosis is essential for wound healing and tissue repair in response to a variety of triggers, which include infection, inflammation, autoimmune disorder, degenerative disease, tumor, and injury. Fibrotic remodeling in various diseases, such as liver cirrhosis, pulmonary fibrosis, renal interstitial fibrosis, myocardial infarction, systemic sclerosis (SSc), and graft-versus-host disease (GVHD), can impair organ function, causing high morbidity and mortality. Both innate and adaptive immunity are involved in fibrogenesis. Although the roles of macrophages in fibrogenesis have been studied for many years, the underlying mechanisms concerning the manner in which T cells regulate fibrosis are not completely understood. The T cell receptor (TCR) engages the antigen and shapes the repertoire of antigen-specific T cells. Based on the divergent expression of surface molecules and cell functions, T cells are subdivided into natural killer T (NKT) cells, γδ T cells, CD8⁺ cytotoxic T lymphocytes (CTL), regulatory T (Treg) cells, T follicular regulatory (Tfr) cells, and T helper cells, including Th1, Th2, Th9, Th17, Th22, and T follicular helper (Tfh) cells. In this review, we summarize the pro-fibrotic or anti-fibrotic roles and distinct mechanisms of different T cell subsets. On reviewing the literature, we conclude that the T cell regulations are commonly disease-specific and tissue-specific. Finally, we provide perspectives on microbiota, viral infection, and metabolism, and discuss the current advancements of technologies for identifying novel targets and developing immunotherapies for intervention in fibrosis and fibrotic diseases.

Keloid treatment: what about adjuvant radiotherapy?

Background: Keloids are debilitating fibrous skin proliferations with a high recurrence rate after surgical treatment. Postoperative radiotherapy (PORT) is a well-tolerated adjuvant treatment to reduce the risk of recurrence, but the optimal regimen for this combined treatment remains unknown. The aim of this study is to evaluate the efficacy of combining surgical excision and immediate PORT.

Methods: We retrospectively reviewed the records of patients with keloid lesions treated with adjuvant PORT in the period 2005–2014 at Geneva University Hospitals. Main outcomes were the rates of complications and recurrence in patients with a minimal follow-up of 1 year, including the Patient and Observer Scar Assessment Scale satisfaction scores.

Results: 10 patients with 16 keloids were eligible (mean follow-up, 37 months). Only one recurrence was reported (6%). In 12.5% of cases, mild erythema appeared in the early postoperative period. No major complications were observed. The overall patient and observer satisfaction rate was excellent.

Conclusion: Surgical excision combined with immediate PORT is an effective and easy treatment with good esthetic results and an acceptable recurrence rate. It should be considered for patients with persistent keloid formation after failure of other treatments and those at high risk of relapse.

Glycerolized Reticular Dermis as a New Human Acellular Dermal Matrix: An Exploratory Study

Human Acellular Dermal Matrices (HADM) are employed in various reconstructive surgery procedures as scaffolds for autologous tissue regeneration. The aim of this project was to develop a new type of HADM for clinical use, composed of glycerolized reticular dermis decellularized through incubation and tilting in Dulbecco's Modified Eagle's Medium (DMEM). This manufacturing method was compared with a decellularization procedure already described in the literature, based on the use of sodium hydroxide (NaOH), on samples from 28 donors. Cell viability was assessed using an MTT assay and microbiological monitoring was performed on all samples processed after each step. Two surgeons evaluated the biomechanical characteristics of grafts of increasing thickness. The effects of the different decellularization protocols were assessed by means of histological examination and immunohistochemistry, and residual DNA after decellularization was quantified using a real-time TaqMan MGB probe. Finally, we compared the results of DMEM based decellularization protocol on reticular dermis derived samples with the results of the same protocol applied on papillary dermis derived grafts. Our experimental results indicated that the use of glycerolized reticular dermis after 5 weeks of treatment with DMEM results in an HADM with good handling and biocompatibility properties.

Site-specific immunophenotyping of keloid disease demonstrates immune upregulation and the presence of lymphoid aggregates

BACKGROUND

Keloid disease (KD) is a common fibroproliferative disorder of unknown aetiology. T cells and macrophages are increased in KD and are thought to contribute to its pathogenesis. However, while a link between inflammation and fibrotic disorders is well known for other disorders, it remains undetermined in KD.

OBJECTIVES

Systematically to immunophenotype the inflammatory infiltrate of KD in situ in a site-specific manner, and to compare this with normal skin and scar tissue.

METHODS

Sixty-eight keloid cases were screened for the presence of all three (intralesional, perilesional and extralesional) keloid-associated specific tissue sites. Subsequently, a complete set of 25 keloid biopsies (from different patients) was compared with normal skin (n = 11) and normal scar (n = 11) samples and subjected to systematic, site-specific quantitative immunohistomorphometry and histochemistry, using a range of immunological markers of B cells, T cells, macrophages, mast cells (MCs) and Langerhans cells.

RESULTS

T cells, B cells, degranulated and mature MCs (coexpressing OX40 ligand) and alternative macrophages (M2) were all significantly increased in intralesional and perilesional KD sites compared with normal skin and scar tissue (P < 0·05). Additionally, 10 of 68 KD cases (15%) showed the presence of distinctive lymphoid aggregates, which resembled mucosa-associated lymphoid tissue (MALT).

CONCLUSIONS

The increased number and activity of MCs and M2 may implicate inflammation in the fibrotic process in KD. The distinct KD-associated lymphoid aggregate resembles MALT, for which we propose the term 'keloid-associated lymphoid tissue' (KALT). It may perpetuate inflammatory stimuli that promote KD growth. KALT, MCs and M2 are promising novel targets for future KD therapy.

Perioperative conditions affect long-term hypertrophic scar formation

Corticosteroids are widely used as treatment for excessive scarring by intralesional injection with variable success rates. It is conceivable that systemically administered corticosteroids affect a wider range of inflammatory processes that influence wound healing and may be more successful in preventing hypertrophic scar formation. To study this presumption, we have used a standardized model of presternal scars caused by cardiothoracic surgery through a median sternotomy incision. During cardiac surgery with cardiopulmonary bypass, 1 mg/kg dexamethasone was administered preoperatively, and 0.5 mg/kg 8 hours postoperatively. The presternal scars were evaluated prospectively 2, 4, 6, 12, and 52 weeks postoperatively at standardized measuring points. The height and width of the scars were measured 12 and 52 weeks postoperatively using both a slide caliper and a 7.5-MHz ultrasound probe. Cardiopulmonary bypass was used in 31 of the 43 participants. Eleven patients (35%) in the dexamethasone group developed clinical hypertrophic scars compared with 4 patients (33%) in the control group. These differences were not statistically significant. However, cranial scars became significantly wider in the dexamethasone group compared with the control group (P = 0.04). Twelve weeks postoperatively scars were significantly higher in the dexamethasone group, both cranial (P = 0.05) and caudal (P = 0.03). The differences in scar width and height were mainly present in patients that developed hypertrophic scars. The present results suggest that administration of high-dose perioperative dexamethasone does not prevent hypertrophic scar formation. Its use together with the cardiopulmonary bypass, however, did affect scar dimensions negatively up to 52 weeks after surgery. These findings contribute to the concept of the involvement of perioperative immunologic responses in the etiology of hypertrophic scar formation.

Reprogrammed fibrocytes induce a mixed Th1/Th2 cytokine response of naïve CD4(+) T cells

Naïve CD4(+) T cells develop different effector T cells and cytokine profiles after antigenic stimulation. It has been previously documented that fibrocytes function as antigen presenting cells inducing proliferation as well as Th2 cytokine response in naïve CD4(+) T cells. Our group has reported that several circulating cell types recruited to the wound site can be transformed into anti-fibrotic profile cells, which subsequently induce MMP-1 stimulation in dermal fibroblasts. Here, we report how similar reprogramming pathway of fibrocytes could modify the CD4(+) T cell response. Our findings confirmed that reprogrammed fibrocytes induce CD4(+) T cell activation with a mixed Th1/Th2 cytokine response. Since a reciprocal positive feedback between Th2 cells and fibrocytes exist to amplify and perpetuate the pro-fibrotic stimulation in dermal fibroblasts, the novel transdifferentiation of regular mature fibrocytes into reprogrammed fibrocytes appears to be a promising strategy to reverse the Th2 cytokine overproduction, and subsequently control the local fibrogenesis.

Gammadelta T-cells: potential regulators of the post-burn inflammatory response

Severe burn induces an immunopathological response that contributes to the development of a systemic inflammatory response (SIRS) and subsequent multiple organ failure. While, multiple immune cells type (T-cells, macrophages, neutrophils) are involved in this response, recent evidence suggests that a unique T-cell subset, gammadelta T-cells are central in the response to injury. While gammadelta T-cells represent only a small percentage of the total T-cell population, they display specific functional characteristics that uniquely position them in the immune/inflammatory axis to influence a number of important aspects of the body's response to burn. This review will focus on the potential regulator role of gammadelta T-cells in immunopathological response following burn and thereby their potential as therapeutic targets for affecting inflammation and healing.

Postburn Scars: An Update

Burn wounds give rise to the largest scars we can find in human pathology, influencing patients' quality of life. Despite the improved knowledge on pathophysiology, efficacy of the various treatments remains unsatisfactory. In this short review recent literature is examined with a focus on recent data on postburn pathological scars epidemiology and risk factors, which underline the high prevalence and the long evolution, pointing to identify this illness as a systemic inflammatory one, more frequent in women and in those of younger age, regulated by local factors relevant in wound healing.

Regulation of the postburn wound inflammatory response by gammadelta T-cells

Healing of the burn injury site is a critical component of the patient's successful recovery from this form of trauma. Previous studies from our laboratory have demonstrated that gammadelta T-cells via the production of growth factors are important in burn wound healing. Nonetheless, the role of these cells in burn wound inflammation remains unknown. To study this, wild-type (WT) and gammadelta T-cell receptor-deficient (delta TCR) C57BL/6 male mice were subjected to burn injury or sham procedure. Wound cells were collected by implantation of polyvinyl alcohol sponges beneath the burn site in injured mice or beneath uninjured skin in sham mice. At 3 days after injury, infiltrating cells, wound fluid, and skin were collected for analysis. Burn injury markedly increased skin tumor necrosis factor-alpha (TNF-alpha) and monocyte chemoattractant protein 1 levels. In WT mice, the numbers of infiltrating cells were similar between nonburn wounds and burn wounds. In contrast, deltaTCRmice displayed a 6-fold reduction in the cellular infiltrate. Burn injury in WT mice caused a marked increase in burn wound TNF-alpha, monocyte chemoattractant protein 1, and interleukin 6 content as compared with nonburn wounds, whereas in delta TCRmice, the burn-induced increase of TNF-alpha and interleukin 6 was not observed. The wound cell infiltrate at 3 days postinjury was devoid of gammadelta T-cells in WT mice. It was predominately of myeloid origin expressing high levels of CD11b and F4/80. In conclusion, these findings suggest that resident gammadelta T-cells are important in the recruitment of inflammatory cells and regulation of the inflammatory response at the wound site after thermal injury.

Sclerodermatous graft-versus-host disease: clinical spectrum and therapeutic challenges

Sclerodermatous graft-versus-host disease (GVHD) is a rare complication of bone marrow transplantation. While GVHD is often associated with the beneficial graft vs. tumour effect, it also contributes towards significant morbidity and mortality. No reliably effective treatment has yet been established. We present 10 patients with haematological malignancies who underwent an allogeneic stem cell transplant and developed sclerodermatous GVHD. Donor lymphocyte infusion administered for relapse or reducing donor T-cell chimerism was a known trigger for sclerodermatous GVHD in four of the patients. Treatment with immunosuppressants, psoralen plus ultraviolet A (PUVA) and extracorporeal photopheresis has been largely unsuccessful in their management. Intensive immunosuppression including the use of anti-CD20 monoclonal antibody may have contributed to relapse of leukaemia in one patient 10 years after her transplant. Sclerodermatous GVHD may occur without a preceding lichenoid stage. Clinical heterogeneity is common, although sclerodermatous GVHD has a predilection for the limbs. Treatment options are largely unsatisfactory if conventional immunosuppression fails. PUVA may give some symptomatic benefit and extracorporeal photopheresis seems to be less efficacious than previously published work suggests.

Koebnerizing sclerodermatous graft-versus-host disease caused by donor lymphocyte infusion and interferon-α

Graft-versus-host disease (GvHD) is a common sequel to allogeneic bone marrow transplants, which may be accompanied by desirable graft-versus-tumour effects. Sclerodermatous GvHD is a rare subtype that is very difficult to treat. We report the first case of sclerodermatous GvHD as part of the Koebner phenomenon. We propose that donor lymphocyte infusion and interferon-alpha were involved in the pathogenesis of this case.

Hypertrophic scars and keloids: etiology and management

Keloid and hypertrophic scars have affected patients and frustrated physicians for centuries. Keloid and hypertrophic scars result from excessive collagen deposition, the cause of which remains elusive. Clinically, these scars can be disfiguring functionally, aesthetically, or both. A thorough understanding of the pathophysiology and clinical nature of the scar can help define the most appropriate treatment strategy. Although many articles have been published on the management of hypertrophic and keloid scars, there is no universally accepted treatment protocol. Prevention of keloid and hypertrophic scars remains the best strategy; therefore, those patients with a predisposition to develop excessive scar formation should avoid nonessential surgery. Once a scar is present, there are many treatments from which to choose. Hypertrophic scars and keloids have been shown to respond to radiation, pressure therapy, cryotherapy, intralesional injections of corticosteroid, interferon and fluorouracil, topical silicone or other dressings, and pulsed-dye laser treatment. Simple surgical excision is usually followed by recurrence unless adjunct therapies are employed. Biologic agents that are directed towards the aberrant collagen proliferation that characterizes keloid and hypertrophic scars might be an important addition to the current armamentarium of modalities in the near future.