Fibroblast growth factor-inducible 14 signalling pathway in cutaneous wounds: a potential therapeutic target.

Epidermal Development and Wound Healing in Matrix Metalloproteinase 13-Deficient Mice

Interleukin 6 Indirectly Induces Keratinocyte Migration

Background:Considering the critical role of early diagnosis and management of acute ischemic stroke, biomarkers that can reliable assist in the diagnosis are still needed. These biomarkers should rapidly analyze, have high specificity for brain damage, and be available in the emergency settings for early diagnosis and exclusion of other conditions that mimic acute ischemic stroke. Soluble tumor necrosis factor-like weak inducer of apoptosis, a protein involved in the regulation of several biological functions, could be a potential acute ischemic stroke biomarker.Aims:To investigate the diagnostic value of soluble tumor necrosis factor-like weak inducer of apoptosis in patients with acute ischemic stroke and examine the relationship between ischemic area volume determined at diffusion-weighted magnetic resonance imaging and soluble tumor necrosis factor-like weak inducer of apoptosis.Study Design:A prospective, case-control study.Methods:This case-control prospective study included 36 patients with acute ischemic stroke and 36 healthy volunteers. Information on age, sex, presence of chronic disease, neurological examination findings, times of presentation to the emergency department after acute ischemic stroke, soluble tumor necrosis factor-like weak inducer of apoptosis levels, ischemic area volumes at diffusion-weighted magnetic resonance imaging, and 6-month mortality rates after stroke were recorded. The results were analyzed on SPSS 22.0 software (SPSS Inc., Chicago, IL, USA), and p<0.05 was considered statistically significant.Results:A soluble tumor necrosis factor-like weak inducer of apoptosis cut-off value of 995.5 pg/mL exhibited a sensitivity of 80.5% and a positive predictive value of 82.5% with an area under the curve of 0.84 (95% confidence interval: 0.74-0.94; p<0.001). The mean soluble tumor necrosis factor-like weak inducer of apoptosis levels in the acute ischemic stroke group (1968.08±1441.99 μg/L) were significantly higher than those in the control group (704.81±291.72 μg/L) (p<0.001). No correlation was observed between soluble tumor necrosis factor-like weak inducer of apoptosis levels and ischemic area volume measured at diffusion-weighted magnetic resonance imaging (r=-0.008; p=0.07). The mean ischemic area volume was 505.68±381.10 and 60.96±80.89 mm3 in the nonsurviving and surviving patients, respectively (p=0.002).Conclusion:Soluble tumor necrosis factor-like weak inducer of apoptosis can be used in the diagnosis of acute ischemic stroke. However, it is inconclusive in estimating ischemic area volume and early mortality following acute ischemic stroke. Ischemic area volume measured at diffusion-weighted magnetic resonance imaging is a marker of poor prognosis and can be used in predicting early mortality.

Calreticulin Enhances Porcine Wound Repair by Diverse Biological Effects

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multipotent growth factor, which plays an important role during the process of wound healing. In clinical settings it has occasionally been employed in the treatment of cutaneous wounds of diverse etiologies. In a previous study, we have shown the positive influence of GM-CSF on full thickness excisional wounds in transgenic mice overexpressing GM-CSF in the basal layer of the epidermis. Direct GM-CSF action as well as indirect processes through the induction of secondary cytokines were proposed to contribute towards the beneficial effects. In this study, we analyzed the process of wound healing in transgenic mice overexpressing a GM-CSF antagonist in the epidermis. These mice not only exhibited a delayed scab rejection and reepithelialization but also neovascularization was reduced. The newly formed tissue was of poor quality as exhibited by the presence of extensive fibrosis. We suggest that the presence of GM-CSF in the repair process is of basic importance and its absence leads not only to delayed wound healing but it is also detrimental for the quality of the newly formed tissue.

Heparin-Binding Epidermal Growth Factor–Like Growth Factor as a Critical Mediator of Tissue Repair and Regeneration

Introduction Skin wounds are frequent injuries that cause heavy financial burdens at both the familial and societal levels with physical and mental suffering. Recently, the attention of researchers has been attracted to the use of exosomes derived from mesenchymal stem cells (MSCs) as a novel non-cell therapy. Aim To study the potential effects of exosomes derived from MSCs on the healing of cutaneous skin wound in adult male albino rats. Materials and methods 47 adult male albino rats were used in this study. They were divided into three groups: group I (control group), group II (cutaneous wound group, that were left for spontaneous healing), and group III (cutaneous wound treated with intravenous injection of exosomes). Each group was subdivided into subgroup a (lasted for two weeks) and subgroup b (lasted for three weeks). A full thickness skin wound was generated through surgery on the back of rats in groups II and III. Exosomes were isolated from bone marrow derived-MSCs through ultracentrifugation. Then, they were characterized by transmission electron microscope. At the end of experiment, skin specimens were collected from all rats and were subjected to proper histological techniques. Results This study showed that MSCs-derived exosomes have significantly improved wound healing, accelerated wound closure, promoted the reepithelialization and the recovery of skin appendages as well as enhancing the organization of newly formed collagen fibers. Conclusion Intravenous injection of MSCs-derived exosomes is effective in healing of full thickness skin wound.

Chronic inflammation develops in the retinal microvasculature under sustained hyperglycemia and is implicated in the pathogenesis of diabetic retinopathy. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 have been reported to promote pro-inflammatory cytokines, which are involved in the pathogenesis of proliferative diabetic retinopathy (PDR). It is therefore possible that the TWEAK/Fn14 pathway can play a regulatory role in PDR. In the present study, we examined the expression of TWEAK and Fn14 in vitreous fluid from PDR patients. To confirm the correlation between the TWEAK expression and clinical pathological characteristics of PDR, we investigated the regulatory role of the TWEAK/Fn14 pathway in cell proliferation and collagen synthesis in retinal ARPE-19 cells. The results demonstrated that vitreous fluid from patients with PDR had higher levels of TWEAK and Fn14 than that from T2DM patients without PDR, thus suggesting an important regulatory role of TWEAK/Fn14 signaling in the pathogenesis of PDR. Furthermore, overexpression of TWEAK in ARPE-19 cells also promoted proliferation of and collagen synthesis in these retinal cells. It is possible that TWEAK/Fn14 upregulation in PDR may contribute to PDR progression by promoting the proliferation or fibrosis of retinal cells.

The interaction of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor fibroblast growth factor inducible 14 (Fn14) participates in inflammatory responses, fibrosis, and tissue remodeling, which are central in the repair processes of wounds. Fn14 is expressed in main skin cells including dermal fibroblasts. This study was designed to explore the therapeutic effect of TWEAK on experimental burn wounds and the relevant mechanism underlying such function. Third-degree burns were introduced in two BALB/c mouse strains. Recombinant TWEAK was administrated topically, followed by the evaluation of wound areas and histologic changes. Accordingly, the downstream cytokines, inflammatory cell infiltration, and extracellular matrix synthesis were examined in lesional tissue. Moreover, the differentiation markers were analyzed in cultured human dermal fibroblasts upon TWEAK stimulation. The results showed that topical TWEAK accelerated the healing of burn wounds in wild-type mice but not in Fn14-deficient mice. TWEAK strengthened inflammatory cell infiltration, and exaggerated the production of growth factor and extracellular matrix components in wound areas of wild-type mice. Moreover, TWEAK/Fn14 activation elevated the expression of myofibroblastic differentiation markers, including alpha-smooth muscle actin and palladin, in cultured dermal fibroblasts. Therefore, topical TWEAK exhibits therapeutic effect on experimental burn wounds through favoring regional inflammation, cytokine production, and extracellular matrix synthesis. TWEAK/Fn14 activation induces the myofibroblastic differentiation of dermal fibroblasts, partially contributing to the healing of burn wounds.

The tumor necrosis factor (TNF) superfamily member TNF-like weak inducer of apoptosis (TNFSF12, CD255) (TWEAK) can stimulate apoptosis in certain cancer cells. Previous studies suggest that TWEAK activates cell death indirectly, by inducing TNFα-mediated autocrine signals. However, the underlying death-signaling mechanism has not been directly defined. Consistent with earlier work, TWEAK assembled a proximal signaling complex containing its cognate receptor FN14, the adaptor TRAF2, and cellular inhibitor of apoptosis protein 1 (cIAP1). Neither the death domain adaptor Fas-associated death domain nor the apoptosis-initiating protease caspase-8 associated with this primary complex. Rather, TWEAK induced TNFα secretion and TNF receptor 1-dependent assembly of a death-signaling complex containing receptor-interacting protein 1 (RIP1), FADD, and caspase-8. Knockdown of RIP1 by siRNA prevented TWEAK-induced association of FADD with caspase-8 but not formation of the FN14-TRAF2-cIAP1 complex and inhibited apoptosis activation. Depletion of the RIP1 E3 ubiquitin ligase cIAP1 enhanced assembly of the RIP1-FADD-caspase-8 complex and augmented cell death. Conversely, knockdown of the RIP1 deubiquitinase CYLD inhibited these functions. Depletion of FADD, caspase-8, BID, or BAX and BAK but not RIP3 attenuated TWEAK-induced cell death. Pharmacologic inhibition of the NF-κB pathway or siRNA knockdown of RelA attenuated TWEAK induction of TNFα and association of RIP1 with FADD and caspase-8. These results suggest that TWEAK triggers apoptosis by promoting assembly of a RIP1-FADD-caspse-8 complex via autocrine TNFα-TNFR1 signaling. The proapoptotic activity of TWEAK is modulated by cIAP1 and CYLD and engages both the extrinsic and intrinsic signaling pathways.

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), along with its receptor fibroblast growth factor-inducible (Fn)14, is associated with various biological activities including inflammation. However, its role in the pathogenesis of Graves’ orbitopathy (GO) is unknown. In this study, we investigated the mechanism by which TWEAK regulates inflammatory signaling in orbital fibroblasts from GO patients. We found that TWEAK and tumor necrosis factor-α (TNFA) mRNA levels were upregulated in GO as compared to non-GO tissue samples. TWEAK, TNF receptor (TNFR)1, TNFR2, and TNFR superfamily member 12A mRNA, and TWEAK and Fn14 protein levels were increased by interleukin (IL)-1β and TNF-α treatment. Treatment with exogenous recombinant TWEAK increased the transcript and protein expression of the pro-inflammatory cytokines IL-6, IL-8, and monocyte chemoattractant protein-1 to a greater extent in GO than in non-GO cells, while treatment with the anti-Fn14 antibody ITEM4 suppressed TWEAK-induced pro-inflammatory cytokine release and hyaluronan production. Additionally, the serum level of TWEAK was higher in Graves’ disease patients with (341.86 ± 86.3 pg/ml) as compared to those without (294.09 ± 41.44 pg/ml) GO and healthy subjects (255.33 ± 39.38 pg/ml), and was positively correlated with clinical activity score (r = 0.629, P < 0.001) and thyroid binding immunoglobulin level (r = 0.659, P < 0.001). These results demonstrate that TWEAK/Fn14 signaling contributes to GO pathogenesis. Moreover, serum TWEAK level is a potential diagnostic biomarker for inflammatory GO, and modulating TWEAK activity may be an effective therapeutic strategy for suppressing inflammation and tissue remodeling in GO.

MMP-13 Plays a Role in Keratinocyte Migration, Angiogenesis, and Contraction in Mouse Skin Wound Healing

Reactive astrogliosis is beneficial in many aspects; however, it is also detrimental in some pathological states such as the development of lethal brain tumors. It is therefore crucial to understand the mechanisms regulating astrocyte proliferation. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor family, was shown to stimulate astrocyte proliferation in vitro. Herein, we further characterize the mitogenic potential of TWEAK on central nervous system cells. Among these cells, astrocytes express the highest level of TWEAK and Fn14 transcripts, suggesting that they are particularly sensitive to TWEAK stimulation. Using in vitro model systems, we found that TWEAK was as potent as epidermal growth factor (EGF) (a prototypical astrocyte mitogen) in mediating astrocyte proliferation. However, its mitogenic activity was delayed compared with that of EGF, suggesting distinct mechanisms of action. Using cell signaling pathway inhibitors, neutralizing antibodies, and protein assays, we further show that the mitogenic activity of TWEAK on primary astrocytes requires stimulation of the transforming growth factor-α (TGF-α) and of the epidermal growth factor receptor (EGFR) signaling pathway through extracellular signal-regulated kinase and p38 mitogen-activated protein kinase activation. In aggregates, our data demonstrate that TWEAK acts as a potent astrocyte mitogen through the induction of a TGF-α/EGFR signaling pathway. We anticipate that description of such a mechanism may allow novel approaches to human pathologies associated with astrocyte proliferation.

Angiogenesis and vasculogenesis: Inducing the growth of new blood vessels and wound healing by stimulation of bone marrow–derived progenitor cell mobilization and homing

Atherosclerosis is a very complex pathology. Over the past two decades we have come to appreciate that a major component of this pathological process is chronic inflammation. This inflammatory state is not only characterized by infiltration of lipid laden macrophages, the hallmark cell of this disease, into the vascular wall, but also is characterized by the infiltration of a host of other inflammatory cells. The complex interaction of inflammatory cells with the normal residents of the vascular wall (ie, endothelial and smooth muscle cells) directs the progression of the disease. Inflammatory cells secrete a variety of chemokines and cytokines which have a profound effect on the development and progression of the plaque. Moreover, many of these cytokines can mediate both pro- and antiatherogenic processes depending on the cellular milieu. The tumor necrosis factor (TNF) and TNF receptor (TNFR) superfamilies encompass numerous cytokines and receptors suggested to play a pivotal role in atherogenesis. Although many members of these families such as TNF-α and CD40 ligand and their putative receptors are considered to be proatherogenic,1–4 studies have also demonstrated an antiatherogenic role for others, including the p55 TNFR.5 TNF-like weak inducer of apoptosis (TWEAK) and its putative receptor, fibroblast growth factor-inducible 14 (Fn14), are also members of the TNF and TNFR superfamilies, respectively. Both TWEAK and Fn14 have been detected in human atherosclerotic plaques, suggesting that these molecules may also play a role in the atherogenic process. Clinical …